Question about double content
 

If I have lets say 50 pages / galleries and all of them have the same html code (same image names, text, etc.) will I get a double content penalty therefore?

Could I prevent a double content penalty by changing part of the title, meta tags (keywords, description), logo alt tag and adding different paragraphs with about 50-100 words at the bottom of every page?

How much same content is too much? |huh |confused|

Yes, if you can change the content it will help a lot.
It helps if you have some different text on the page as well as different page titles. I think these are the main factors.