Bug fix: Adjustment for multiple reference to the same label. The solution is still...

Bug fix: Adjustment for multiple reference to the same label. The solution is still not optimal as any reference to a label after the reference will not get notice. This is because addToToc() is called iteratively through the document so the toc entry for the label is still not created... any idea to fix this is welcome.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@23285 a592a061-630c-0410-9148-cb99ea01b6c8