How to quickly compare the similarity of an office file with a list of existing ones?

Question

PHP

The essence of the question is as follows - there is a database of office files (doc, docx, ppt, pptx, xls, ..).
How to check its existence in the database when adding a new file in php.
File names can be anything.
The number of files in the database is 1000-5000.
From the ideas - to re-index the existing database, get what hashes you have (which ones are better?) And compare them with the hashes of new files. The minus of the method is that small changes will lead to a change in the hash and, accordingly, the duplicate will pass the check.
Maybe there are some other ways?