The Multico is a brilliant machine, great buy.
Which ever way you either pulled or pushed the spanner to get off one block, pull, or push in the same direction for the other block. The threads as stated above are LH and RH, but as one block is upside down you pull or push the spanner in the same direction for both. The block orientation takes care if the thread direction.
I bought mine really, really cheap as the bloke I bought it off could not work out why the tennons it cut were not square and even along their length. I've since found that this can be a problem with any of the machines that's been stripped down and is really easy to fix. The key is that the table must be set to be exactly square and parallel with the two rods / rails it runs on. Mine does not have adjustable (off centre camb) bearing rollers so to get it right it was just a question of moving around the roller mounts until it properly aligned. I think the table and fence are skimmed after the table was mounted to the two rails.....but I could be wrong.