I'd drain the contaminated oil, seals tend not to like gasoline.
If it is not going to be very long until the carbs are cleaned up, I'd leave it without oil or filter and put a big note on the handlebars, hide the key also with a note on it and/or undo the negative battery cable. You obviously don't want you or anybody else spinning over with no oil.
If you want to refill it go ahead, I don't think there is much negative to changing the oil and putting on a new filter as long as the carbs have no gas and nobody turns the gas on. I would not waste the money to do it twice in a row, when the bike hasn't gone anywhere.
Although I do like to warm up the engine before draining under normal circumstances, it a cold engine sits for a few hours with the plug out, it will drain anyway unless the temperature is in the -30's.
This is probably confusing, but that's how my head thinks.