well, you know how we are getting that summoned mount? will we still be able to keep our normal horse that we don't summon aswell? ( im thinking about getting shadowmere, but i don't want to do all the DB quests and then just have it dissapear forever after the DLC )

Yes, you just have to not summon your horse

in an interview Todd said it was from a side quest,so you dont have to get the horse

I remember Matt saying in an interview that, while you are in Soul Cairn, you must find a skull or something, and then the horse will be available for summoning.

I know that, what was i wondering was if it replaces your current horse?... I hope it doesn't lol, because that means im not wasting my time with the DBH

No as the new mount in the DLC is from a side quest and is totally optional. If you do want the mount but already have a horse, your current horse will simply return to the place you got it from on its own. Then again, you can always not summon it.

i know its optional, i was also just hoping to have both shadowmere and the one with flames

You can't have both as your horse at the same time. You can have one as your current horse and the other will always be at it's starting location ready for you at all times.

You cant have your sweetroll and eat it too

That's why I carry two Sweetrolls.

Also, what if the Horse you summon wears off while you ride it?