Why adobe can’t save file with the same name?

hi zeinab24355458zcng,

Thank you for contacting us. When you choose "Save a Copy" from the context board menu, then select other location than the current file location, the file will be saved with the same file name. Otherwise, as your experience, it will create a copy of the file with the name has "(x)" in the same file location to avoid overriding the original document accidentally. 

Please give us feedback in the link below,

https://acrobat.uservoice.com/forums/914680-acrobat-reader-for-ios

Sorry for any inconvenience.