I don't think it is possible, as the nic is already attached to the vSwitch. The vm's that are attached to that vSwitch are able to communicate with each other. From the NIC attached, they can then communicate to the outside world. Especially if you want to keep the same configuration with the 2 NICs on the same vSwitch. You will need to give up the other NIC and create a separate vSwitch for the Backup. Teamed NICs must have same VLAN configurations. For more information, see https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/support/landing-pages/virtual-support-day-best-practic…
It's not possible to allocate a dedicated NIC in a vswitch if it's in active. If you want you can configure NIOC in a VDS and assign a specific bandwidth for Backup jobs.
Refer the below for NIOC configuration,