I wish my load ran in 200 seconds.
Interesting that there's a difference like that, a few things possible, like REORG'ing might help get the pages in the right order. Could also be fragmentation on your filesystem if you're using SMS or DMS with file containers.
Are you specifying the INDEXING MODE, or letting db2 AUTOSELECT? (default) If the default, maybe it's doing an INCREMENTAL on one node and a REBUILD on the other?
Just a few thoughts.