If it were me, I would have asked the director:
"Why isn't the lighting the exact same on the beach as it is in the hallway? Why didn't you place the key light in the exact same spot and have the same exact exposure and backlight as you had from the sun on the beach than the florescent light in the hallway? Lighting guys I know would have lit the scene to match perfectly in the different locations - it's called Green Screen. So, give me money for ADR if you need it to match. Sorry if it didn't occur to you that different locations can look different but not sound different."
If someone is standing in a hallway and a beach, the resultant recordings will sound different - period. And, sorry, I'd like to hear a recording done on a beach sound the exact same as the hallway shot with the exact same amount of ambient noise like this director is asking you for. Anyone got one? It doesn't exist. I agree you could get the same tonality, but ambient noise? A beach creating 80 dB of white noise compared to a quiet hallway? Wow.
The correct thing you should have done was figure out what microphone you could have used and worked in each location, which would have the most rejection of reflections and stick with that as your main mic and use the other as a backup. Based on what I read, I think a Lapel would have worked best, first because if you plant it on his neck tie or shirt, you've got somewhat of a natural baffle and closeness to the source, and it will be pretty similarly placed in each of the locations and you would have minimal reflections if you placed it correctly. The key for these shots is using the same mic in the same spot to achieve a consistency. Then mix it to match - start with one scene, get it sounding good, then move on to the next and match it best you can.
What I suspect happened is you're using a chesty lav and trying to match it with far-miced boom mics and that's the difference he's hearing. Do you have a lapel recording throughout the whole thing? I'd drop everything and swap out all dialogue to be that mic - that would be the best possible match, I think. Otherwise, live and learn, do it better next time and don't dwell on your mistakes - learn from them and move on. You're only smarter now. We've all made mistakes. Don't let it happen again and do better next time.