Hi Randy,
In the good-old-days, I used a dry-mount press. It's still the best way today. My problem was always mounting them top to bottom rather than top to top...
Your best bet is to use a jig to align this way and a tacking iron.
As an alternative, print oversize and then carefully trim the excesses. In any case, I usually have to trim just a little no matter how well I mount the prints back-to-back since I always seem to print my page signatures on large sheets cut from rolls.
In the past several years, I've printed my pages on my Epson 9800 and then cut them and glued them together using spray mount. It's a little bit of a pain but doable. This is the technique I've used to make several hand-made and hand-bound books of prints and portfolios. It takes time and expect to have some waste when you do them this way.
I've also run the Inkjetart.com two-sided matt paper through the 9800. It takes some effort to do successfully since the paper curls quite a bit. My solution is to print side one, let it dry, iron the paper to flatten and then rotate 90 degrees to print side two. It's not perfect but it works! I sort of wish that Epson had the 2-sided matt in other than 8.5x11 inches, but as it was, this was the only 2-sided, 24-inch wide paper I've been able to quickly find. Great to do a large and folded broadsheet for a portfolio intro!
HTH,