I'm looking for a program that can copy/paste large number of files quickly for Windows 7. If it finds a file in the source folder that shares the name of a file in the destination folder, it should have options for automatically handling such conflicts. For example, I can tell it to compare the file sizes, and if the sizes are the same, skip copying the file from the source folder; otherwise, rename the file from the source folder and copy it to the destination folder. I've tried several different programs so far, including WinMerge, FastCopy, and SuperCopier, but they either overwrite without asking, give you the same endless conflict error windows that Windows already offers, or just plain lacks anything like the features I'm looking for. Does such a program exist?
Have you tried Copywhiz - http://www.conceptworld.com/Copywhiz . I think it would meet your requirements.
Description from the website:
When copying files, Copywhiz can rename duplicate files so that you can keep both versions of the file (the original file & the file being copied).
When the first duplicate file is detected, Copywhiz will ask you if you wish to replace it. You can opt to rename the destination file with a suffix instead of overwriting it. Or you may also rename the file that is being copied.
You can copy only newer or modified files by skipping identical files. This will make the copy process much quicker. It is useful if you are backing up your files to the same destination. Only new & changed files are copied.
Also, to ensure that the destination file is not replaced with an older version of the file you can skip files that are identical/newer in the destination folder.
Eg. When maintaining a set of music files on yet another drive (USB pen drive, music player etc), you can select these options to update the collection with only newer or updated files saving you several minutes each time.
You can choose 'Do it for all files" to automatically rename the files.