How to quote from the same document? For example
SECTION 3. Explanation
Before discussing the main theorem, let's quote it's statement.
Theorem 7.1. (Main lemma) 1 + 1 = 2
...
SECTION 7. Appendix
Theorem 7.1. (Main lemma) 1 + 1 = 2
Notice that I'd like the theorem be numbered as "7.1." even in section 3. This cannot be done simply by copying and pasting, or by using packages like clipboard.
Putting it differently, I'd like to copy a specific region shown in the compiled file and paste to another.