No, this feature cannot be disabled. You should always use unique filenames.
Duplicate filenames within a single folder are not permitted - this being true of any computing system. While your iPad is no different, how it avoids conflict may differ to other computers with which you may be familiar. Some Operating Systems simply won’t allow files with duplicate filenames to be copied to an existing folder; iOS/iPadOS instead allows the move to occur, but removes the conflict by adding a <space> and a number to the duplicate file.
To avoid issues such as you describe, you should avoid naming your files in a manner that may cause issues - i.e., [filename]<space>[number] - as this is the filename construct used by iOS/iPadOS to remove conflicts.
Instead, perhaps consider using [filename][number] (i.e. without the space) or at least an alternative to the <space> character - such as an underscore (“_”), this being commonly used as a substitute for <space> within filenames.
In following this advice, you will avoid the issue that you describe. While iOS/iPadOS will continue to resolve filename conflicts by appending a number (with a space) to filenames, your own file-naming will not be altered.