I, too, always take off the extra "melody" string. I use a thumb-pick to give a bit of emphasis to the notes played on that string against the other two strings (which I chord). I always found the doubled strings tended to jam together and get all jangly. Of course the first, mountain-made dulcimers I played were all simply three-stringers.

I also prefer the old 1-5-5 (D-A-A) tuning (the D being the lower, wound string). Almost all the current dulcimer whiz-kids play with a 1-5-8 (D-A-D') tuning. This requires a dulcimer with the 6 1/2 fret, of course, which the older mountain-made instruments didn't have. That innovation allows the regular major scale to be played on the octave-tuned "melody" string. Skipping that extra fret, one gets what we used to call the mixolydian mode, without the sharpened leading note. Many of the recent dulcimer instruction books are written primarily for instruments having this additional fret, so check to be sure yours does before you invest.

Sandy (cheerfully old-fashioned)