Swifties only dispute one of Kerry's 3 Purple Hearts - the first one for his shrapnel wound on Dec 2 1968. The alleged witness who claims foul play is Dr. Lewis Letson - However the medical record shows Kerry was treated by medic J. C. Carreon who is conveniently dead. The claim is that this wound wasn't bad enough, because the treatment was basic first aid - a distinction not made for determining the validity of such an award.
Kerry faces questions over Purple Heart - The Boston Globe
There are no claims that Kerry was hit by his own grenade launcher

- However one of the swifties that didn't know Kerry had received a Purple Heart for receiving shrapnel from his own grenade launcher.
The second medal in dispute is Kerry's Bronze star for bravery under fire. Kerry was criticized by Larry Thurlow who said that there was no enemy fire that day. However, Thurlow himself also received a bronze star for the same incident that day. The commander who issued Thurlow's Bronze Star stated "under constant enemy small arms fire"
Records Counter a Critic of Kerry (washingtonpost.com)
Kerry's medals were deserved, says widow of slain comrade - The Boston Globe
The third medal in question is Kerry's silver star by George Elliott. Who apparently changed his mind in 2003. Originally Elliott had this to say about Kerry's Silver Star "The fact that he chased armed enemies down is not something to be looked down on." Elliott also said - the award was "well deserved" and that he had "no regrets or second thoughts at all about that."
ABC News: Morning Show Wrap, by ABC News Political Unit
Boston Globe Online | John Kerry: A Candidate in the Making
but in 2003 Elliott signed two affidavits that criticize the award -
Talk about your partisan view
Veteran retracts criticism of Kerry - The Boston Globe
Kerry = True War Hero