I've checked the latest vmware.log file and can see the following references to the strange disks:
Feb 28 13:59:22.531: vmx| DISK: OPEN scsi0:0 '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01.vmdk' persistent R[]
Feb 28 13:59:22.585: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01-delta.vmdk" : open successful (10) size = 6459273216, hd = 43337944. Type 8
Feb 28 13:59:22.585: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01-delta.vmdk" (0xa)
Feb 28 13:59:22.585: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01.vmdk' (0xa): vmfsSparse, 41931698 sectors / 20 GB.
Feb 28 13:59:22.598: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01-ac1eb6efaa73e4a-flat.vmdk" : open successful (14) size = 21469029376, hd = 41634009. Type 3
Feb 28 13:59:22.598: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01-ac1eb6efaa73e4a-flat.vmdk" (0xe)
Feb 28 13:59:22.598: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01-ac1eb6efaa73e4a.vmdk' (0xe): vmfs, 41931698 sectors / 20 GB.
Feb 28 13:59:22.598: vmx| DISKLIB-CHAINESX : ChainESXOpenSubChain: numLinks = 2, numSubChains = 1
Feb 28 13:59:22.636: vmx| DISKLIB-LIB : Opened "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01.vmdk" (flags 0xa, type vmfs).
Feb 28 13:59:22.637: vmx| DISKLIB-LIB : Content-ID check is now enabled.
Feb 28 13:59:22.638: vmx| DISK: Disk '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01.vmdk' has UUID '60 00 c2 92 c4 06 0e b3-98 03 88 9f aa 9d de 6e'
Feb 28 13:59:22.638: vmx| DISK: OPEN '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01.vmdk' Geo (2610/255/63) BIOS Geo (0/0/0)
Feb 28 13:59:22.639: vmx| DISKLIB-CTK : Auto blocksize for size 41931698 is 128.
Feb 28 13:59:22.705: vmx| DISKLIB-CBT : Initializing ESX kernel change tracking for fid 43337944.
Feb 28 13:59:22.705: vmx| DISKLIB-CBT : Successfuly created cbt node 1d548da-cbt.
Feb 28 13:59:22.705: vmx| DISKLIB-CBT : Opening cbt node /vmfs/devices/cbt/1d548da-cbt
Feb 28 13:59:29.042: vmx| DISKLIB-CBT : Exceeded max. # of ioctl calls when looking for in use disk areas. Marking remainder of this from offset 538136064 as in use.
Feb 28 13:59:29.044: vmx| DISK: Change tracking for disk scsi0:0 is now enabled.
Feb 28 13:59:29.101: vmx| DISK: OPEN scsi0:1 '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1.vmdk' persistent R[]
Feb 28 13:59:29.149: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1-delta.vmdk" : open successful (10) size = 8707481600, hd = 638062256. Type 8
Feb 28 13:59:29.149: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01_1-delta.vmdk" (0xa)
Feb 28 13:59:29.149: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1.vmdk' (0xa): vmfsSparse, 104858304 sectors / 50 GB.
Feb 28 13:59:29.160: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1-9ace2ad6c00b0c6-flat.vmdk" : open successful (14) size = 53687451648, hd = 596250289. Type 3
Feb 28 13:59:29.160: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01_1-9ace2ad6c00b0c6-flat.vmdk" (0xe)
Feb 28 13:59:29.160: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1-9ace2ad6c00b0c6.vmdk' (0xe): vmfs, 104858304 sectors / 50 GB.
Feb 28 13:59:29.160: vmx| DISKLIB-CHAINESX : ChainESXOpenSubChain: numLinks = 2, numSubChains = 1
Feb 28 13:59:29.222: vmx| DISKLIB-LIB : Opened "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1.vmdk" (flags 0xa, type vmfs).
Feb 28 13:59:29.223: vmx| DISKLIB-LIB : Content-ID check is now enabled.
Feb 28 13:59:29.224: vmx| DISK: Disk '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1.vmdk' has UUID '60 00 c2 9a 6a 8b 54 7e-9d c3 6d a4 59 74 36 61'
Feb 28 13:59:29.224: vmx| DISK: OPEN '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_1.vmdk' Geo (6527/255/63) BIOS Geo (0/0/0)
Feb 28 13:59:29.225: vmx| DISKLIB-CTK : Auto blocksize for size 104858304 is 128.
Feb 28 13:59:29.268: vmx| DISKLIB-CBT : Initializing ESX kernel change tracking for fid 638062256.
Feb 28 13:59:29.269: vmx| DISKLIB-CBT : Successfuly created cbt node 23150eb2-cbt.
Feb 28 13:59:29.269: vmx| DISKLIB-CBT : Opening cbt node /vmfs/devices/cbt/23150eb2-cbt
Feb 28 13:59:31.298: vmx| DISKLIB-CBT : Exceeded max. # of ioctl calls when looking for in use disk areas. Marking remainder of this from offset 65626624 as in use.
Feb 28 13:59:31.305: vmx| DISK: Change tracking for disk scsi0:1 is now enabled.
Feb 28 13:59:31.337: vmx| DISK: OPEN scsi0:2 '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2.vmdk' persistent R[]
Feb 28 13:59:31.364: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2-delta.vmdk" : open successful (10) size = 100687872, hd = 141052211. Type 8
Feb 28 13:59:31.364: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01_2-delta.vmdk" (0xa)
Feb 28 13:59:31.364: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2.vmdk' (0xa): vmfsSparse, 20999004 sectors / 10.0 GB.
Feb 28 13:59:31.392: vmx| DISKLIB-VMFS : "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2-c90359261cca5b0-flat.vmdk" : open successful (14) size = 10751490048, hd = 140396852. Type 3
Feb 28 13:59:31.392: vmx| DISKLIB-DSCPTR: Opened [0]: "NEXDBTV01_2-c90359261cca5b0-flat.vmdk" (0xe)
Feb 28 13:59:31.392: vmx| DISKLIB-LINK : Opened '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2-c90359261cca5b0.vmdk' (0xe): vmfs, 20999004 sectors / 10.0 GB.
Feb 28 13:59:31.392: vmx| DISKLIB-CHAINESX : ChainESXOpenSubChain: numLinks = 2, numSubChains = 1
Feb 28 13:59:31.410: vmx| DISKLIB-LIB : Opened "/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2.vmdk" (flags 0xa, type vmfs).
Feb 28 13:59:31.411: vmx| DISKLIB-LIB : Content-ID check is now enabled.
Feb 28 13:59:31.412: vmx| DISK: Disk '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2.vmdk' has UUID '60 00 c2 90 97 9f 64 ec-78 71 60 59 ec 49 50 86'
Feb 28 13:59:31.412: vmx| DISK: OPEN '/vmfs/volumes/4a28f09b-87f7b050-64a4-001e4f441d75/NEXDBTV01/NEXDBTV01_2.vmdk' Geo (1307/255/63) BIOS Geo (0/0/0)
Feb 28 13:59:31.412: vmx| DISKLIB-CTK : Auto blocksize for size 20999004 is 128.
Feb 28 13:59:31.515: vmx| DISKLIB-CBT : Initializing ESX kernel change tracking for fid 141052211.
Feb 28 13:59:31.516: vmx| DISKLIB-CBT : Successfuly created cbt node 7aa4935-cbt.
Feb 28 13:59:31.516: vmx| DISKLIB-CBT : Opening cbt node /vmfs/devices/cbt/7aa4935-cbt
Feb 28 13:59:32.778: vmx| DISKLIB-CBT : Exceeded max. # of ioctl calls when looking for in use disk areas. Marking remainder of this from offset 816310784 as in use.
Feb 28 13:59:32.780: vmx| DISK: Change tracking for disk scsi0:2 is now enabled.