If someone copies Bitcoin's code and creates another currency from it, have they created a second Bitcoin?

Detailed explanation

Bitcoin Core is released under the free MIT licence. Anyone can inspect, copy and modify the code. An unchanged copy running with Bitcoin's network parameters is initially just another software instance that can connect to the existing Bitcoin peer-to-peer network and validate its blocks. It does not create a new asset.

Anyone who changes parameters, the genesis block or the rules and starts a separate network begins a different history. That network does not automatically possess Bitcoin's existing UTXOs, accumulated proof of work history, nodes, miners, wallet infrastructure, users, trading pairs or liquidity. Those features emerge through actual participation and shared use.

Even a fork from an existing history remains a separate network with its own future once the rules diverge. Source code is therefore important, but Bitcoin is more than files. It is the interplay of rules, validated history, a communications network, economic participants and voluntary social coordination. Copying code can reproduce functions; it does not automatically copy the entire system.