Not at the moment, but it's something we'd like to add, the ability to turn games you own multiple copies of to gifts.
Thanks for the response! I'll probably get the bundle regardless. Like I said, my copy of Hustle Cat was bought directly on Steam. If you did add a feature, it would be great if it gave you the gifting option upon purchase, rather than only checking if the buyer has the game on Itch already.
In my awkward situation, I already had two on steam, two on itch.io. This bundle is not held for donating any organization, it is really difficult to pick up. Maybe it is nice and fair to cut the percent of price for people who already had some of them in it, rather than turning it as gift because these are not some kind of team group games, such as Invisigun Heroes which would be better to stay in the gift system reversely.