Relative URLs, Multiple bindings

Hi,
Some queries regarding the URLs returned by a PROPFIND.

Assume that we have a collection A/B/ and two members A/B/x and A/B/y.

1. When a PROPFIND is issued for A/B/, is it a MUST that the return URLs are
A/B/x and A/B/y (that is always relative to the parent), or is it possible
that completely different URLs are returned. 
For example, if we maintain some unique identifiers for the resources in a
global path, say VCRs/, then we could probably want to return VCRs/1234
(representing x) and VCRs/5678 (representing y). Is this allowed?

2. Is it possible that two bindings are pointing to the same Resource? To
illustrate, assume that we had the resource A/B/x and another collection
P/Q. Now both A/B and P/Q is checked-out. x is moved from A/B to P/Q. After
this, we do an UNCHECKOUT on A/B and a CHECKIN on P/Q. Now both A/B and P/Q
have bindings pointing to x.

Regards,
Girish