A man with a blue, collared shirt sits in front of another man.
a man sits in front of another man
Answer: A man sits in front of another man
They both have the same phrasing (front of another man) sentence 2 is just less specific.
All of sentence 2 ( a man sits in front of another man) is found inside sentence 1, the only difference is that sentence 1 describes the first man's appearance.