ERC721 CID Url

I'm trying to understand how ERC721 CID url's work.

How can i use the same CID url multiple times such as



Do i have to do this in the same instance call, or how can i reuse the CID?


There is not built-in mechanism checking duplication of IPFS CIDs, however, you can add a mapping and a function to check for duplication, or any logic you'd like to impose on CIDs.

Not sure i understand your reply. I'm trying to reuse the CID

I mean ERC721 does not have a built-in mechanism checking CIDs. Instead, you may want to add the following code in your ERC721 contract.

mapping(string => uint256) _CIDUsage;

function usageIncrement(string memory CID) internal {
    _CIDUsage[CID] += 1;

function getCIDUsage(string memory CID) public view returns (uint256) {
    return _CIDUsage[CID];

It will allow you to put restrictions on CID usage, like duplication, or maxNumberOfDup, etc.