Some difference, but mostly of the cosmetic variety.
Uncharted Dual Pack contains a slipcover case which houses two Greatest Hits red label versions of Uncharted 1 and Uncharted 2 GOTY. The UPCs on the back are "not for resale", and since it is a North American release for both US and Canada, there will be both English and French text on the box art which makes it look slightly more cluttered. You are guaranteed the GOTY DLC voucher code from Uncharted 2 GOTY if you buy new, although it might be expired by now (I recently had an unscratched off voucher past expiration that did not work, other people have reported that theirs did)? IMO, since you'll already have Uncharted 3 GOTY for multiplayer, the GOTY stuff for Uncharted 2 is not that important. It contains multiplayer map packs, skin packs, and some short motion comics and PSN avatars.
Uncharted 1 used could be the original black label or the Greatest Hits red label. Red label probably has more recent patches already on disc, but otherwise there is no difference in content between the two or the version from the dual pack.
Uncharted 2 GOTY used could be the original black label or the Greatest Hits red label. Red label probably has more recent patches already on disc, but otherwise there is no difference in content between the two. There is no GOTY content on disc in either version or the dual pack version, it is all DLC on the voucher code, so most likely a used copy will not contain a valid code. In other words, without the voucher Uncharted 2 GOTY is functionally the same as Uncharted 2 vanilla.
Finally, the used prices you are considering are ridiculously high. The last few weeks off and on, Amazon Warehouse Deals has been clearing out tons of used copies of Uncharted 1 and Uncharted 2 for $5 each. Gamestop also has both used at $10 each.
