I would like to get a new exit node IP addresses each time I get a new Identity and most of the times it works but sometimes I get the same ones as before. Is there an option to remove duplicate exit IP addresses at least for 24 hours?
If one is really interested to do what you are looking for, and does not want to go the easy way of requesting a new identity, there are ways to do this. One of these solutions will be presented here. But be advised that this solution is tedious, and nobody probably have ever used it, because it is much more cumbersome than requesting a new identity. Now that you have your warning! here it is:
You start the Tor Browser and record your exit node IP address. Once you are done with this session of Tor browser and want to request a new identity, do not do so. Close the Tor Browser, and edit your torrc file. Add these lines to torrc file:
You need to enter the identifying information of the last exit node at the place of node in ExcludeExitNodes command and save the torrc file and start Tor Browser again. You will need to repeat this process every time you are done with a given exit node and add the second, third, forth, and so on exit nodes that you have used to the torrc file. Very tedious and cumbersome task as I warned you beforehand.
For additional information look at this quote from Tor manual:
A list of identity fingerprints, nicknames, country codes and address patterns of nodes to never use when picking an exit node---that is, a node that delivers traffic for you outside the Tor network. Note that any node listed in ExcludeNodes is automatically considered to be part of this list too. See also the caveats on the "ExitNodes" option below.
And this quote from Tor manual:
If StrictNodes is set to 1, Tor will treat the ExcludeNodes option as a requirement to follow for all the circuits you generate, even if doing so will break functionality for you. If StrictNodes is set to 0, Tor will still try to avoid nodes in the ExcludeNodes list, but it will err on the side of avoiding unexpected errors. Specifically, StrictNodes 0 tells Tor that it is okay to use an excluded node when it is necessary to perform relay reachability self-tests, connect to a hidden service, provide a hidden service to a client, fulfill a .exit request, upload directory information, or download directory information. (Default: 0)
Additional information beyond this is availble in Tor manual: https://www.torproject.org/docs/tor-manual.html.en
There is no option to do that because changing identity frequently without anonymity in mind is frowned upon as it increases network load. Tor wants to be a tool that allows anonymity, and thus "new identity" creates a new session unlinkable to your last, but not necessarily using a fresh exit node. People have tried using Tor to game vote casting systems etc, which makes it harder to run exit nodes and is considered abuse.
There are ways to do what you are looking for, but it is much more hassle than requesting a new identity if you did not like your previous identity. Thus, clicking new identity bottom more than once, if you did not like a new identity you get the first time. In any case clicking a new identity bottom should not be that much of a hassle.