This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
There appears to be no requirement that a redeclaration of an alias template must be equivalent to the earlier one. An alias-declaration is not a definition (6.2 [basic.def] paragraph 2), so presumably an alias template declaration is also not a definition and thus the ODR does not apply.
Rationale (November, 2014):
This issue is superseded by issue 1896.