As people have said, there are some programs designed by third parties, like EVE-O Preview, which help can help players manage monitor space for multiple clients. A key nuance here is that each client does need to be controlled by the user. What you have described sounds like using a program to mirror commands to multiple clients simultaneously, known as input-broadcasting. Doing this is a violation of the EVE Online ToS and EULA, and will result in an immediate ban on all accounts.
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