"Six string" dulcimers that actually are three strings double-coursed are fairly common, but had Guest SPGWK read the whole thread he might have notice that this instrument is described as "strung like a guitar" - i.e. with six equally spaced strings.

(Some of the regulars here aren't always too good at reading before commenting, so that's not much of a criticism.)

Unless one has incredibly fat fingers (which may be the case for that GUEST) playing the strings as "double courses" would appear to be rather difficult. Two separated strings tuned in unison can perhaps be used in some tunings, but describing them as "double coursed" is probably not accurately descriptive.

It should make no difference which end the tuners are on, unless they're located so that they impede getting to the strings at the strum/pluck/whack area. You can't pull harder on one end of a string than on the other (without the string flying out the window) so it doesn't matter much which end winds up the slack.

The comment about "the frets are backward" is a bit of a puzzle. As long as they're spaced farther apart at an end and get closer together as you move toward the middle, they're probably conventional, if perhaps "left-handed." The person making the comment may have looked only casually once the unusual tuner location was noticed.

Having assembled a couple of dulcimers from "kits" I can attest that the instructions are seldom particularly explicit, and it's entirely possible that someone assembled some parts backward, resulting in something that looks like an instrument but really isn't. Those who've bought most kits might buy another for the parts, but if they're intelligent enough will use the intructions only to sop up the glue that gets spilled (for most kits).

"Experiments" are common enough - and frequently enough are "less than successful." Without knowing who made it, guessing what the builder thought it was supposed to be is likely to be somewhat pointless.

Thre is a minor increase in loudness with double-coursing of the strings; but if double-coursed strings really made an instrument all that much louder, shouldn't the mandolins drown out all the guitars?

A picture of the instrument (probably easier to post and link now than TEN YEARS AGO WHEN THE THREAD APPEARED) might elicit more useful comments, but one might expect that the instrument is hanging on a wall - or otherwise misplaced and "forgotten" by now.

John