When the cards are on the same LAN it never helped even a little. Since traffic at the lowest level is sent by MAC address what did you do to get traffic to that other NIC?
Sorry if that's a hard question but you are going where users rarely go.
I have a workstation Dell T3500 with 2 NIC cards installed.
We are using Broadcom Advanced Server Program for teaming both NIC cards on one IP address.
It has been observed that both LAN Connection is enabled,but status(send/receive) of only one LAN connection is updating, whereas the traffic(sent/receive) on another LAN connection established is zero.
Also the icon of LAN connection looks like disabled,but it show's enabled at the bottom.