FYI This question refers to the "stick to one brand" theory/myth.

I put a fresh new tape in to camera_[A] to record, then take the recorded tape to camera_[B] to playback the footage, then put the tape back in to camera_[A] to record over the previous footage.

note:
camera_[A] Has ONLY used ONE brand of MiniDV Tape
camera_[B] has used VARIOUS brands of MiniDV Tape's

My question is:

Will the tape contaminated/dirty camera_[A] heads after it's been playback from camera_[B]
?

As a rule I use only fresh tapes right out of the cellophane in my cameras. I know of other pros who do the same.

Swapping tapes isn't worth the risk of contaminating a camera whose primary function is to gather material reliably on the first pass.

I know what you mean about reusing tape for experimentation with video methods. I swap the same tape over and over because I do not care about drop outs while I am taping specifically for finding the look that I will be taping when I find what I am looking for.

Here is what I have done based on what I have read. I don't have enough time to say it works. I also cannot say that one camera test means much anyway.

1. The first tape should contaminate the most. I think I would never reshoot on it from the point I played it on camera 'b'. I would record on 'a' capture on 'b' and then record only from the point of the tape with 'a'.

2. After 60 minutes of the first tape, I assume the cross contamination that could possibly exist is stuck to the heads of camera 'b' already or picked up by tape 1.

3. The minimal residue of tape 2 will barely be around for problems or a big bunch of gunk will drop off of camera 'b' onto the tape and then transfer from the tape to camera 'a' at some point in time.

My deck is a used camcorder with unknown tape use. I used a head cleaner when bought and reuse tapes at my own risk between it and my camera 'a' with no bad effects. Maybe I use the same tapes as the former owner? Maybe the same brand thing is over paranoid?

I think points 1-3 are the things to think about in this case. Maybe others will chime in.