Question on hidden rows..

I need to know if the following is possible. Let's say on Sheet 1 I have data in rows 1 through 20 and on Sheet 2 I have data in rows 1 through 40with the odd numbered rows hidden (leaving 20 visible rows). Is there a way to copy data from the 20 rows on Sheet 1 into the VISIBLE 20 rows on Sheet 2? When I attempt to do this manually, it obviously pastes data into the hidden rows as well, so rows 21 through 40 aren't updated. I have seen lots of posting about copying data with visible/non-visible rows, but not PASTING data into a sheet with non-visible rows... Possible, or impossible?