On Steam: No. Only one build can be installed at a time. Opting in to the Experimental branch replaces your default installation, and switching back replaces the Experimental one. You can move between the two whenever you like — each switch just downloads the relevant changes rather than keeping both versions.
On Xbox: Yes. The Experimental build installs alongside your default installation, so both can be present at once. This does mean it takes up additional storage space, but you can launch either one without waiting for a download.