The other day I had an agent write a parser for a niche query language which I will not name. There are a few open source implementations of this language on github, but none of them are in my target language and none of them are PEGs. The agent wrote a near perfect implementation of this query language in a PEG. I know that it looked at the implementations that were on github, because I told it to, yet the result is nothing like them. It just used them as a reference. Would and should this be a licensing issue (if they weren't MIT)?
I'm more interested in the general question rather than the specifics of this situation, which I'm sure is now incredibly common. I know it looked at those implementations because I asked it to, and therefore I will credit those projects when I release this library. In general though, people do not know what other material the agents looked at in order to derive their results, therefore they can't give credit, or even be sure that they are technically complying with the relevant licenses.