How to catalog a product without duplicates?

Question

Cataloging

Hello!
An online store with similar functions as Yandex Market is being created. There are 2 questions:
Question 1: there are about 30-40 file tables with a list of goods. each table has about 5 thousand products. It is necessary to combine all tables and products, but so that the products do not repeat, but are connected and appended to the main table (adding new information, including about sellers). Thus, one product will have several sellers.
The problem is that the products in different tables have different names. For example: A.S. Pushkin "The Bronze Horseman", The Bronze Horseman - Pushkin, Alexander Sergeevich Pushkin - The Bronze Horseman
and so on. Lots of spelling options.
Question 2: after creating a catalog, online stores will themselves compile their own catalog in a table and add it to our website through a special form. (by analogy with Yandex Market).
How, when compiling such a table and importing to us, the goods will not be duplicated in the main table, but complement each other? Do you need to give each product of the original table its own article and the program will navigate by it?