Only the first ones that you have received and spent! Go to your profile page and click your achievements. Somewhere in there are the achievements for earning the first emblem for each giant and the achievements for spending an emblem for each giant.
There isn't a listing but you can figure out how many you received by calculating from your favor limit. If your favor limit is 1000 then you haven't received any. If it's 1100, then you've received 1, 1200 = 2, 1300 = 3 etc. You can tell if you've spent your first emblem by looking at your Achievements page.
The reason I spend emblems more than once is that it raises the limit for that giant. The first time you 'buy' an emblem it is 1000, the second 1100, third 1200, etc. I am at 1800 on several giants at this point. That means I can contribute up to 1800 points and cash them in to accelerate skill training on that giant each day. It also means that each successive emblem is 100 points more expensive, of course. So I 'lose' the difference between the amount each emblem costs and the 1000 that it can be cashed in for, but my limit increases.