Example 2 does not create any TLD conflicts. TLD is supported by both Alternative Roots. Example 3 creates a TLD conflict. Both Alternate Root A and Alternative Root B have .biz TLDs, but these TLDs are not coordinated, or peered, and therefore duplicate zones may exist. Example 4 creates a TLD conflict.
Alternate Roots do in fact exist.
No one can prevent them from existing, because the selection of a root zone to point to is a voluntary act by DNS name server administrators and end-user client software. Name Conflicts Name conflicts are generally considered a bad thing. So far, so good. Obviously, if there is a disagreement, it is possible to create a duplicate TLD, in a different root, and managed by a different party. Disagreements are caused by a number of factors.