# MetaMask

By [sahe](https://paragraph.com/@asyncmusic) · 2022-05-08

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When you go to add another Mainnet RPC endpoint, you may see a message stating that the Chain ID is already in use by the Mainnet network. Since you do in fact want to add a new Mainnet network, click “Save” and it will work.

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*Originally published on [sahe](https://paragraph.com/@asyncmusic/metamask)*