A moment to butt in. If you get interested in double needles, please remember that you cannot sew stitches any wider than the hole in the stitch plate of your machine. My elderly Bernina can make a single needle zig zag up to 9 mm so if you are doing a fancy stitch with at least a double needle, you will need to check about that side to side thing and the two needles.
Have a good time with playing with various kinds of needles. P S, they make great gifts - ask my husband.
Pat