Quite frankly, it is possible if you're willing to go back and forth multiple times between tabs. Otherwise, an easy way is not possible due to staff not having possession of the source code to program that function into the game.
What I mean by it's possible, is that I've done it before. Same account, or separate.
I personally only did it to save a character that I would've otherwise lost due to needing to delete some characters.
For the same account, just open two FH tabs, do NOT move the window if it loads directly on top of the first. But if it doesn't, you need to line up both tabs perfectly on top of each other. Log in with one, and go to the desired character and edit. Then, on the second tab, log in there with the same account and make a new character. (Note: This will log you out of the first tab due to the last tab you loged in with takes over the primary session.) To get the proportions to be the same, on the new character once you've selected wolf or lion, move them to around where you have them set on the original. Switch back to the tab with the completed character while looking at the dials without closing the first and see how much you need to move them back or forward. (I would suggest doing this one by one, once completing one dial to save the character and edit it again so it saves you from having to do the tedious work again in case it glitches and freezes on you.) Switch tabs and adjust, then switch tabs again, watching the dials, to see if they match or are close to. Keep adjusting as needed until you can switch tabs and the dials don't move an inch. Now if you're like me, then I always make sure they stay exactly the same. Consistency! lmao
For separate accounts, once again open two FH tabs. On the login page on your browser, log out, then log into your second account. On the second FH tab, repeat what was said for "copying" your character to the same account.