Hypothetical question:

Let's say you have 100 in smithing, and all the perks in it except for the last one (you already have glass and daedric perks). If you take the last perk will you be able to craft both dragonscale and dragonplate armor or is the game going to choose one for you and you will never be able to craft the other one? Or can you take the perk twice and craft both types? Would like to hear from someone who has actually done this if that person exists and still looks at this forum.

You can craft Dragonscale Armor, Dragonplate Armor, and Dragonbone Weapons from that one perk. Only 1 point is needed.

Indeed. Once you take the perk, you can craft everything the perk provides. There are no limitations.

Yes, and it's a really nice thing about it too if you want to hook up a follower with a set of armor since killing dragons provides both scales and bones.

Cool. thanks for the answers. I thought if you went up the left side you could only make light armor and if you went up the right you could only make the heavy version.

You can only make Steel plate armor by going up the light armor side of the tree, despite it being a heavy armor............not only that, but Daedric armor is actually the best kind of armor (despite it being lower in the tree than Dragon), but Dragonbone weapons are the best weapons in the game.............no, it makes absolutely no sense.

Same thing with Nordic Carved. It requires the Advanced Armors perk. And Stalhrim Light Armor requires the Ebony Smithing perk. Chitin Heavy Armor uses the Elven Smithing. 'Tis all over the place.