Originally posted by Veseljko:

I think this is so rare you don't even need to think about it. I played 3000 hours and used the same technique of getting back to base for repairs and rest during my long journeys and I've seen it happen only once.
I think the problem is in no tag part, not in portal itself. Try naming your portals instead of using no tag portals.

Looks like tag won't prevent that from happening. OP was teleported to the previous portal location with the same tag (even though all three portals were nameless). Bet if they used one tag for all temporary portals, same thing would've happen.