No, at least not operationally, because when a unit changed the type it operated it converted over a period of time when it and all its personnel were not operational.
There are possibilities for this to be a relatively short period. For example, in the RAF it might be possible for a Lancaster pilot to be posted somewhere he would fly the Halifax or Sterling with which he may have been familiar, but even then he would have undergone some 'refreshment' before becoming operational.
The difference between a qualified pilot and an operational pilot is something that even some reputable historians have failed to grasp
Cheers
Steve