When dragging a word or selection of words to the project search, it should always make a copy of the selection, regardless of whether the alt key is held or not.
It’s not like we could potentially be trying to move it somewhere else.
The search field not actually being a place.
It is also unfortunate that holding the alt key, if it allows to make a copy of the selection dragging it from one place to another within a single document, it doesn’t work with a split editor, both showing the same document. (Say you’d have one editor showing the top of the document, the other the bottom. Alt+drag doesn’t work.)