That's what it looks like. 2 rows of a double-hem. Probably just adjusting the side stop after the first pass.
Speed is never a problem with sewing machines. If anything, they need to be throttled (you'll get used to it -- but if multiple people are on the machine -- it's best to change the gearing ratio, or adjust the peddle stop). I'm upgrading my sewing machines right now to an electric Juki with a servo motor so the speed can be set electronically (among other things, like having giant U bobbins). Just about any industrial double-needle walking foot sewing machine will work for your project though. You can pick up a good used machine (preferably 30-40 years old, like a Singer or Mitsubishi if you want an old reliable workhorse without all the bells and whistles), or something newer like a Juki or Seiko. Prices often range from 1.5k-4k respectively for a good used machine+table (keep 'em oiled and they will last forever). Beware of new Singers though -- they are made in China (plastic parts). That's why people like the older ones. Or if you get into new machines with servo motors (i.e, computerized versions with auto-cut, etc) -- those types of features automatically double the cost of the machine ($7-8k). Japan makes great machines (Seiko, Juki), both with and without servos. In any case -- beware of eBay rejects. Always test in person or purchase from a reputable source. Be handy enough to make timing adjustments yourself or check around locally to see if anyone knows how to work on industrial machines.
