Wordpress tags with dollar sign collides with the one that does not have dollar sign

We are prefixing $ sign to some tags to associate certain meaning like $FOO but then it is treated same as FOO whereas we want them to be treated as two distinct ones. Looks like slugs for both ends up as "foo" and when we try to add tag $FOO when FOO exists already it is ignored.

Is there any way we can override this behavior of slugs (say for tags alone) ? Understand that slugs are there for a reason, so is there a way to create a taxonomy that would allow co-existence of both "FOO" and "$FOO" ?

Using WP version 4.5.2.

via Chebli Mohamed