Yes.
The Threadiverse has multiple intercompatible "Reddit-alike" software packages.
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Lemmy (the biggest). Example: https://lemmy.world/ Written in the Rust programming language.
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PieFed. Example: https://piefed.social/ Written in the Python programming language.
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Mbin (the successor of the defunct Kbin project). Example: https://fedia.io/ Written in the PHP programming language.
There's also Sublinks, written in Java, but I don't know for sure whether that's going to actually get the ball rolling. https://demo.sublinks.org/ Think they need more developers contributing.
EDIT: Note that while this approach is unusual for the centralized Web-oriented social media era, where typically one company controls the whole shebang and has one codebase, it is common for federated systems. There are many different NNTP server implementations for Usenet, many different XMPP server implementations for instant messaging, many different IRC server implementations for chat, many different SMTP server implementations for email, many different FidoNet implementations.