Is my 12 month old sleeping too much?

So I have 12 month old twin boys and they have been sleeping SO MUCH recently! I didn't really think about it being an issue until my husband pointed it out. So they go to be at 7 P.M and wake up at 10 A.M then they sleep for 2 hours during the day. So that's like 17 hours between night and day?! I don't know if I should be concerned or if they're just growing, but it seems like they're sleeping too much! Any suggestions/advice would be greatly appreciated as I am a FTM.