Not at all. Everything depend on local situation. Use directional antennas with different frequencies on both links, place them at least 1m away from each other on the site B and there will be no problem.
You can put some grounded metal sheet between the two devices on site B to be absolutely sure.
My question is… Will two APs on a pole interfere with each other just as much as an AP and Station on the same pole. All other variables remaining the same… Spacing, weather…etc.
Both radios will spend time sending and receiving. Moments where radio1 is listening while radio2 is transmitting could cause interference if you’re not following best practice for installations, channel planning, etc - it doesn’t matter which is the AP and which is the station.
If you’re using a frequency duplexing sytem, (such as Nstreme dual) then you can make all transmitters use the same frequency because they can’t interfere with each other.