Doctors sharing the same adventure

I think that, for a laugh, Big Finish should make Shada again with Tom.

Jon Pertwee and Colin Baker in 'The Ultimate Adventure'. As for stretching it, both Doctors had this same adventure at least thirty times each.

The Seventh Doctor experienced Remembrance of the Daleks twice, except the second time around they called it Silver Nemesis.

I was thinking of the Gareth Roberts Shada. How do you explain that?

That's a very Moffat-y explanation. Are you Steven Moffat?

Regardless, I find that a plausible solution actually. That'll be my head canon from now on.

I wonder if Moffat will canonise both versions of Shada before he leaves?

More importantly, when are the Pertwee UNIT stories set?

Both are incarnations that seem to be wiser to their own temporal inconsistencies, so that makes sense.

Of course, if we're counting novelisations, we're missing one enormous occurrence of twinning that's dogged the show's footsteps since virtually its conception -- the Target novelisations. Jo Grant is introduced twice and remembers Wenley Moor, Ian and Barbara didn't know each other before the car crash on Barnes Common, the First Doctor both rests in the sleep compressor and regenerates on the floor of the TARDIS and Mel is dropped off on Oxyveguramosa at the end of The Ultimate Foe.

We're caught in a chronic hysteresis! There's also a third incarnation played by David Banks who appeared which fans have taken to calling the Greenpeace Doctor. Placement becomes doubly hard when you consider that Pertwee flubbed a line and Third called Crystal "Sarah Jane" by mistake.

No they aren't.  I grew up pre available VHS recordings and read and reread them, and they aren't.  The most used device is the unnamed narrator, which Dicks favoured a lot. Don't let audio readings confuse the point on that.