What is there to confirm? Just read the cards. Twinflame creates a token that is a copy of a creature that is already on the battlefield. If you cast gray merchant and it resolves bam you get the ETB. Then if you cast twinflame and copy merchant and it resolves you get the etb again. Just read the card.
Lets say you drop Burning-Tree Emissary then Twinflame the BTE and drop another creature or spell. In a sense this could mean 8 BTE and if you have it right you could possibly have
Turn 1 - Land, Boros Elite
Turn 2 - Land, BTE 1, TF BTE 1, BTE 2, TF BTE 2, Firefist Striker
Attack for 7
Turn 3 - Legion Loyalist
3 Battalion triggers, creature opponent controls cant block, your creatures gain trample and first strike
Attack for 10
You could have 4 BTE (a bit unlikely) but now you could have 8 making getting more in your opening 7-10 cards. Im sure there are more better examples the this card being used.
Turn 1 - Land, Boros Elite
Turn 2 - Land, BTE 1, TF BTE 1, BTE 2, TF BTE 2, Firefist Striker
Attack for 7
Turn 3 - Legion Loyalist
3 Battalion triggers, creature opponent controls cant block, your creatures gain trample and first strike
Attack for 10
You could have 4 BTE (a bit unlikely) but now you could have 8 making getting more in your opening 7-10 cards. Im sure there are more better examples the this card being used.