If Spinehorn Minotaur gains double strike only after combat damage has already been dealt (most likely because another creature’s ability caused you to draw a card when it dealt combat damage), Spinehorn Minotaur will deal only normal combat damage.

Spinehorn Minotaur’s effect applies even if you drew two or more cards only before Spinehorn Minotaur entered the battlefield.

If a spell or ability causes you to put cards into your hand without specifically using the word “draw,” Spinehorn Minotaur’s effect doesn’t count them.