Before you start your project, learn the distinction between NFT and FT.

Non-Fungible Token or Fungible Token

As you already noticed, NMKR Studio allows you to create Non-Fungible Tokens as well as Fungible Tokens.

Non-Fungible Token

A Non-Fungible Token is a completely unique Asset...

Fungible Token

Unlike Non-Fungible tokens, Fungible tokens are about as "un-unique" as you can possibly get. They are completely interchangeable, have identical value and are indistinguishable from one another.
A good way to think about "Fungible" is thinking about FIAT money. From the point of view of trading, the £10 Note in your hand is EXACTLY the same as the £10 Note in someone else's wallet or the TWO £5 Notes on your table.
Note - this analogy is slightly wrong, as you may know that physical bank notes have a serial number on them. For the purpose of this explanation, pretend that they don't.
Similarly, $1 = $1, 1 BTC = 1 BTC, 1 ADA = 1 ADA and crucially there is simply no concept of 'I want THAT specific ADA' because there is no specific ADA, only an amount of ADA held in a wallet.
That, is what is means to be Fungible.

Duplicated NFTs

You may have noticed that we have a guide for creating Serialised Duplicate NFTs. This is a different concept, so it is important that we outline the difference.
A duplicate NFT created with NMKR Studio is an NFT that has the exact same media and metadata, other than a slightly different Token Name and Display Name (Numbering / Serialization).
In this context, Duplicate NFTs would be the addition of a Serial Number associated with what would technically otherwise be a fungible Token. Because they have a serial number, it is possible for a person to say that they hold 'item number 6127' or that they want to purchase 'item number 777'. This minor difference is what makes the tokens Non-Fungible (although in a sense, you could argue that these are almost 'semi-NFT's').