xcversion install does not detect that "10 beta 6" is installed

[quacktacular]

If Xcode 10 beta 6 (in this case) is installed, running xcversion list shows that it is installed.

So I would expect that running a subsequent xcversion install "10 beta 6" would return "Version 10 beta 6 already installed." But instead it tries to install over top. What's going on?

[quacktacular]

Also I can't select...

 xcversion select "10 beta 6"
[!] Version 10 beta 6 not installed.

For reference here is my list

$ xcversion list
4.3 for Lion
4.3.1 for Lion
4.3.2 for Lion
4.3.3 for Lion
4.4
4.4.1
4.5
4.5.1
4.5.2
4.6
4.6.1
4.6.2
4.6.3
5
5.0.1
5.0.2
5.1
5.1.1
6.0.1
6.1
6.1.1
6.2
6.3
6.3.1
6.3.2
6.4
7
7.0.1
7.1
7.1.1
7.2
7.2.1
7.3
7.3.1
8
8.1
8.2
8.2.1
8.3
8.3.1
8.3.2
8.3.3
9
9.0.1
9.1
9.2
9.3
9.3.1
9.4
9.4.1 (installed)
10 beta 6 (installed)

[JonnyBeeGod]

Same issue with Xcode '10 GM seed'

[JonnyBeeGod]

Workaround: xcversion installed prints out the version identifier you need for xcversion select See screenshot

[landonepps]

The same thing happens with Xcode 12 beta. Thanks for the workaround @JonnyBeeGod 👍