Thank you so much for your help! I actually looked at the documents/info I had already collected, including that manifest you reference and noticed the dates were very similar so the Declaration must be wrong.

It really got me to wondering tho, how my greatgrandfather could be off on the ship name when that incorrect ship name actually did come in in Dec of 1907 along with his actual ship. I wonder if others try to help the immigrant's recall by going with what info he has and trying to fill in the blanks, for instance, he might have remembered he came in Dec of 1907 but not the exact date or the ship. Looking at records, the person helping him might have seen the SS Pres Grant came from Hamburg in Dec 1907 so they put that on the declaration.