I can only speak for The Patriot Game, which was written by Dominic Behan, a prolific writer of Irish songs. Behan did in fact accuse Dylan of ripping off The Patriot Game. But anyone who knows the lyrics can see there is no rip off of the lyrics, while there is a vague similarity in the subject the words differ substantually. He did indeed use the same tune, but any Iriosh song scholar will tell you that the tine used by Behan ws itself lifted from a very old trad Irish tune, so Dylan was only using the age old Folk process of using an already used tune to good effect of and which was out of copyright. Behan was kn own for these little temperamental outbursts, and often accused other performers , such as The Clancy Bros of things they were not guilty of.

Finally, Dylan is a prolific writer, who freely credits such performers as Guthrie, Paxton, Seeger, The Clancy's, Behan's and many others as influences. It'd be surprising therefore if he DIDN'T write stuff that may have strong similarities to existing works. but that goes for most Folk writers