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Well, in the case of the OP, the alternative is the manufacturer: https://www.ifixit.com/Tools

Be free! Install all the DEs/WMs your heart desires.

Regarding the multiple entries for X and Wayland versions of a particular DE: for the most part, I think xwayland has solved this, but as always–for better or worse–you have the freedom to go either way.

This is the first time I’ve heard of this, and I pretty much always have more than one DE installed and have never run into issues. Assuming you’re using a display manager (SDDM, LightDM, etc.), it should handle loading whichever graphical session at the time of login properly.

edit: For clarity, what do you mean by “installing another DE *on top * of an existing one”–like kludging two DEs together in the same X/Wayland session? If so, that sounds like a horrible mistake that lead to that happening.