#5916 fix multiple drop things

[ondrelogin]

Summary

Creating a copy of the class level _things and iterating over the copy to Drop the items instead of the actual original list.

[IEvangelist]

Summary

Creating a copy of the class level _things and iterating over the copy to Drop the items instead of the actual original list.

I tried this out locally, you're correct! I like the changes, but wanted to stay closer to the original version. If we just call .ToArray it creates a new instance.