I immediately got 4 Gold Fafnirs... when I get ~20 seeds again, I'll spend 16 to MUB one, repeat.
I actually made a spreadsheet for calculating the dupe chances (and chance of getting someone I want) for using it or waiting today, hah. I was trying to figure out if it was worth finally using my free one (I've saved it for... a while now) before doing the dream summon, but as is I guess I should just buy Hildegarde and save it. So I could give you a copy of that to fill out if you want.
EDIT:
Here, quickly made it its own sheet and added pretty colors. You should be able to copy it so you can edit it. For the third column, put "H" if you have them, "Y" if you want them, and "N" (or nothing) if you don't want them.
Rest should be obvious. If you want to fiddle with numbers to see what happens if you naturally got more of one of the groups, there's the "editable" boxes at the bottom. Just undo after to make it go back to the formula of copying the other cell.