Many thanks for your solution, which seems very elegant.

(1) I tested it with two tabs, each tab has two columns of data, works great. Is it possible to have the results eliminate the redundant rows?

So if I have:
1 a
1 b
2 a
2 c
2 d

I currently get

1 a b
1
2 a c d
2
2

(3) I have some tabs with more than two columns of data (there is no set rule as to how many columns there might be). Will it work with this?