4.12 "Module Import" says:
"It is a static error if the expanded QName of a variable declared in an imported module is equal (as defined by the eq operator) to the expanded QName of a variable declared in the importing module or in another imported module (even if the declarations are consistent) [err:XQST0049]."

I believe we intend that the error doesn't occur if the variable(s) declared in the imported module(s) is/are private.

(Note that the appendix blurb for XQST0049 says:
    "It is a static error if two or more variables declared or imported by a
    module have equal expanded QNames (as defined by the eq operator.)"
which avoids this problem because private variables are not "imported".)