Bug/Issue Double 'special' items

Issue: I keep getting doubles of items that are in a set location/chest. Mayor's shorts, slingshot, Robin's axe, other chest items in the mine (example: crystal dagger.) I am unable to get rid of the slingshot and Mayor's shorts, etc. as those are not able to be sold, thrown away, or gifted. I tried to give the Mayor his shorts twice and it said, "wrong person."
I was able to do this multiple times (not wanting to,) but I could only get 2 of the Mayor's shorts.
Operating system: macOS High Sierra
I was in full screen mode.
Other info: I use no mods, I just updated to the "jumpingjunimos" beta yesterday. Unsure if this was an issue before I updated to the beta.

 

I also had this issue with the Mayor's shorts. I cannot get rid of them either.

 

best solution I can think of is to put all of those things in a chest and put it in a highly trafficked area, say outside the saloon. NPCs walk into it and will delete it. No more duplicate items. As for the cause, buggy beta is buggy.