Frank Mentzer:

" I wrote module R1 "Falx" as an RPGA tournament, and R2 "Hydell" for the 1980 DM's competition, which I won. Those are thus solidly TSR properties... but the two following items, R3/4 Egg of the Phoenix & Doc's Island, tho used as RPGA tourneys, were based mostly on materials I had written in the 1970s, long before joining TSR. I have several witnesses who played those adventures in the Philly suburbs. The campaign I developed prior to 1980, and all materials I have written since 1988, are my sole property. "

I just found this to be interesting. Here is a link to the whole thread:
Dragonsfoot • View topic - Q&A With Frank Mentzer. Part 1