most of the blocks built into EQ are public domain.
if you surf the net you will find hundreds of patterns that look virtually the same, all made using public domain blocks. the authors of those patterns can easily claim copyrights to their images and instructions. whether or not they would win a fight in court over exclusive rights to their layouts and fabric combinations is questionable.
so far, my research leads me to believe a designer would have to prove that hers is the first use of that combination and that it is so unique, there is no reasonable possibility that somebody else in the world could possibly have thought up that combination on their own. in the event of conflict, she'd have to prove that she designed hers first and that there is no way you could have come up with yours without copying hers. i think one or two have won a case but i never worry about it when my designs are based on blocks from the public domain.