What's wrong with JackJackWallet? Even JackWallet or WalletJack sounds nice to me, and I'm not even an American, English is my 1.5st language.
I volunteer and allow you to use my name. heheh... royalty free. I just want to be famous for 15 minutes or whatever.
I have nothing against them, but it seems the latter carries a negative connotation.
(American) English is my mother tongue, and I agree that JackWallet carries a negative connotation. I don't want someone to jack my wallet. "WalletJack" seems less negative, but I'd still stay away from it,
And JackjackWallet is definitely too pedantic. As would be Gavin-qt or EtotheipiClient.