Port plug question

Hello!

I'm fairly new to the HiFi scene (essentially got into it about 2 years ago) and I would love to know if it's okay (for any part of the setup) to plug a single speaker's rear port and not the other? Due to space constraints, I have a pair of Elacs B6's arranged where one is closer to a corner than the other. The left speaker is about 2' from either wall, and the right one is 2' from the rear wall and miles away from side wall. With the way this is set up, I can hear a slight imbalance where more bass appears to be coming from the left speaker. When I partially plug that one's port, the effect is reduced nicely. But will plugging only one create any issues for the speakers as a pair? I'd like to make it clear that I have never kept one plugged for more than 2 minutes, so it's not my current arrangement.

Thank you!