You can merge using menu > merge option from right to left or left to right. because it highlight the different keyword or line from the file, so you can merge it togather. When you want to merge two different files say about text or word file, you will see the different. Once you scroll down cursor, you will see both files will be simultaneously scrolling down and you can find out for difference between two files easily. You can open both txt file in left and right windows. It gives you minute comparison, say you want to compare two identical txt files. It will show comparison result with left date & right date option with extension option.SO it would be easier for you to find out for you which files are duplicate. I have created some identical files with similar name for trial.

Say if you want to compare one folder from your USB drive & another from your Local drive of your computer, you can choose both of them.Once you click okay, it will start comparing folders from your selected location. When you open folder to compare, you can select file or filder to left and another on right, so there will be two location selected for comparing. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle. WinMerge is an Open Source differencing and merging tool for Windows.

Sharing it, how you can use winmerge with your computer to compare and merge duplicate files/folders. I searched a lot and find one software winmerge, that I tried and seems useful. I have copied several files to PC which occupies too much space because of duplication of same files. The same was happened to me while backup my external 1 TB Western Digital harddisk, so its hard to remember all 1 TB data. Most of the time while we backup data from our computer to another computer/laptop, sometimes we forget which files/folders we have copied and bymistake we copy folder/files twice.

Winmerge compare folder