Backup Exec can use teamed NICs however what we have experienced with such setups is that the average BE/Server Administrator might understand how to use the setup tool on their windows server, but rarely understand the requirements on their network switches and/or specific advanced options, which means we have sometimes seen teamed setups run slower than unteamed ones (and means we do often ask customers to test with the team disabled to show such issues)
You can use a backup LAN between a Backup Exec server and the remote servers it backs up, by installing secondary network cards. However for this to work well, you must configure name resolution from the BE server to remote servers and remote servers to the BE server so that the resolution between them returns IP addresses on the backup LAN for those network conversations. As in most environments DNS would need to return the production LAN for any other traffic this usually means using local hosts files (which for some companies might be affected by their software security processes). We do kind of discuss secondary LAN setups in this document https://www.veritas.com/docs/100020481
We did also have a recent customer that for their own reasons had configured a huge number of IP addresses (50+) on their Backup Exec Server (as a mixture of physical cards and VLANs) and this caused a crash in one of our processes. We do intend to fix this condition in future release (and it will probably only be fixed in the current BE version (20.x), as such for the time being don't setup a Backup Exec server with lots of IP addresses.