no, the the theory of time used in doctor who is that if a person goes back in time and changes an event it results in a changed future no alternate dimensions or universes are created (this is easily debunked by the fact that the tardis every now and then travels to an alternate universe and this only happens because of tears in space-time). if a person changes an event that would result in a paradox, the universe (or the timelords when they were still around) correct the paradox and the tardis has systems built in to prevent paradoxes from happening. (if it created alternate universes when it traveled through time, paradoxes would be irrelevant and wouldnt need correcting). however there are only points in time a time traveler can go that can actually impact future events (these result in small changes that don't make a difference in long term events), then there are fixed points in time that a time traveler can not go or can go but can't change major events.

a change in fixed point of time would result in a paradox that will either be resolved by another event or will cause a tear in the universe.
this is why the doctor is very selective about who he travels with, where he goes, and what he does, because if he altered a major event too much it could result in the deaths of thousands