Why not make every URL that's shown in the title bar a permalink by default?
That way, you have the best of both worlds in all cases.
If another object tries to use the same URL as another object (which was used first), then a new URL must be generated (just add something at the end of the name).
Because then you are compromising the utility of your url-as-search semantics, complicating your implementation, and probably distorting your data and/or schema. A better solution is to make the distinction between "display" and "permanent" url a first class concept.
That way, you have the best of both worlds in all cases.
If another object tries to use the same URL as another object (which was used first), then a new URL must be generated (just add something at the end of the name).