By 'tomorrow', I meant I had to go look at the difference for myself right away.
Admittedly the leaves do look pretty similar in these pics, but you can see the difference in lobes somewhat. The fruit comes in much differently. BM comes in with this pale green upright fig then it stays the same for a while then one day swells up big and purple then turns black. Figo Preto has much darker green straight fruit that speckles black onto the green then just fills in black. At least that has been my experience with them this year.
My Black Madeira also tasted significantly better than my Figo Preto.
All of these are my Black Madeiras right now: