> Can't see why it would cause the judge any problem?
Trying to work out if they are a seen dog, or where they are to stand in the challenge (though I suppose it isn't the judge but steward that can get confused) and of course you do need to be careful to check you have got the correct numbers pinned on.
My strangest swap the dog incidents have been where a Friend has taken in my other dog when I have had the fortune to win a class with both my exhibits, only for them to be pulled out the winners, and thinking well done you, and then having to realise ti was my dog :)
Also a bit of a fluster is caused when the judge needs the second in the class to the winner for the chalenge (and your already in the ring) as usually a back up handler hasn't been arranged.