I don't have time to do this in depth right now, but I looked up samples of Poggio's handwriting. They are pretty consistent, in a neat Italic book hand. Even his notes are written in much the same style and his inscription notes show that he had a sense of design and balance as far as the layout of the page is concerned.
There are also some samples claimed to be his that don't look like his hand (the manuscripts don't even look right overall, they look like they are from earlier time periods). Some are fuzzy, low-res examples, so it's hard to tell, but others look more like the kind of manuscripts that he was copying rather than his copies, so I wonder if some people on the Web are mistaking the original (that Poggio copied) for his copy? It's hard to be sure and would take legwork to sort out.
There are also some samples claimed to be his that don't look like his hand (the manuscripts don't even look right overall, they look like they are from earlier time periods). Some are fuzzy, low-res examples, so it's hard to tell, but others look more like the kind of manuscripts that he was copying rather than his copies, so I wonder if some people on the Web are mistaking the original (that Poggio copied) for his copy? It's hard to be sure and would take legwork to sort out.