I have given walt both of his required items and I still have the faux bust. I can't see to offload it on Fahd. He keeps saying he needs a replacement for the one I stole. Help!!

that's cuz you need both when talking to fahd. If you already given walt the bust, you can't complete the one with fahd.

is this not some mistake?

Fahd shouldn't know that the real bust has been placed in the museum yet, should the fake bust not still be possible to get sold?

I didn't have the fake one when I sold the other to Walt. I didn't think it made any difference. What jorian said makes perfect sense, why can't you sell the fake one without the real one, Fahd doesn't know what happened to it.

not sure of the reasoning since I just know how this is completed. (at least, I'm pretty sure. could be wrong lol)

shaz/tini will need to come over to clarify

maybe this could be handled as something that needs a fixing

Yup. Its not really clear even in the FAQs section.

This is working as intended. Going on your own logic, why would Fahd buy one off you just because he knows you have two? He doesn't know you have any.

Sorry, sometimes you have to do things in a certain order, or you miss out on doing them. Most of our games have had things like this in them. It's not related to a quest, though sometimes there are also quests that you have to do a certain way, or at a certain time, or they just stay in your journal.