How do I remove duplicate Google Tag Manager scripts from my theme header?

Duplicate GTM scripts must be manually isolated and removed from your theme’s header template files (header.php or theme.liquid) to prevent inflated traffic counts and browser execution lag.

“Most minor website breaks are caused by simple script conflicts, legacy code blocks, or broken API handshakes. We identify and clear these issues immediately as a straightforward, one-time fix.”
— Jeff Bollettino, Managing Director, Ignite Conversions