It would be beneficial to allow for more than one pay method field on a gift record if a donor would like to make a donation but use multiple methods of payment (say cash and check) to make it. Also, allow these fields to be access in all data entry locations like Batch and Import.
I would consider this to be 2 gifts. I have at times used a pledge to kind of "link" them together though because I know that this can be helpful for reporting.