Where do I look for an exact timestamp?
Hover your cursor over the approximate timestamp to see the precise time (to one second) in UTC. The trailing
Z is short for Zulu time.
Should the second one be marked as a duplicate?
Marking as duplicate is done by voting. If you would like to ask "Is this a duplicate" then write that out as your actual question.
Question 1 was in fact the duplicate so why was the older question marked as the duplicate?
Marking as duplicate is a Stack Exchange function to bring future readers to the best answer. It doesn't have any specific connection to the sequence of asking. "I was here first" thinking shouldn't be applied.
Similar question-asking happens once in a while. It's hard to judge in this case, both questions are pretty short and their original titles don't exactly match the questions asked in the original texts.
As always it's best to worry about getting one's questions to be clear in the beginning. I think both were written hastily and could have been written more carefully and thoughtfully, but there are two good-quality answers to this one. Closing the other one as duplicate brings future readers to those answers, so the other should stay closed until it's rewritten to ask a substantially different question that would require substantially different answers.
I was here first! and It's not fair! are unbecoming ways to view the Stack Exchange experience.