The screenshot suggests that you are using the classic Fiddler where similar functionality is not implemented.
However, this forum is for Fiddler Everywhere, in which each composed request could be saved, shared, and re-opened at your will.
Hello Fiddler Team!
How to open many Composer in Fiddler? I want send many request with different body at the same time.
I try open 2 Fiddler but program just open 1 Fiddler.
Sorry for my english!