The problem

1. See in the Terminal that "Hello" Command is send twice.
2. For better visibility change the Hello-Command to something else. Did that for Klipper to restart firmware.

Can be reproduced with virtual printer. It is also interessting that after Changing monitoring state from "Connecting" to "Operational" the original Hello-Command is send again and not FIRMWARE_RESTART. Or better I would no expect that it is send again.

Did the issue persist even in safe mode?

Yes, it did persist

If you could not test in safe mode, please state why ("currently printing" is NOT an excuse!)

Yes

Version of OctoPrint

1.10.2

Operating system running OctoPrint

OctoPI 1.0.0

Printer model & used firmware incl. version

Anycubic Mega S - Klipper v0.12.0-290-g14a83103c FIRMWARE_NAME:Klipper

Browser and version of browser, operating system running browser

Windows 11 - Edge 128.0.2739.67

Checklist of files to include below

• Systeminfo Bundle (always include!)
• Contents of the JavaScript browser console (always include in cases of issues with the user interface)
• Screenshots and/or videos showing the problem (always include in case of issues with the user interface)
• GCODE file with which to reproduce (always include in case of issues with GCODE analysis or printing behaviour)

Additional information & file uploads

logs.txt
octoprint-systeminfo-20240913082832.zip

Terminal log in Safe Mode with virtual printer:
Changing monitoring state from "Offline" to "Opening serial connection"
Changing monitoring state from "Opening serial connection" to "Connecting"
Connected to: VIRTUAL(read_timeout=10.0,write_timeout=10.0,options={'enabled': True, '_config_version': 1}), starting monitor
Send: FIRMWARE_RESTART
Recv: start
Send: FIRMWARE_RESTART
Recv: Marlin: Virtual Marlin!
Send: FIRMWARE_RESTART
Recv: \x80
Recv: SD card ok
Recv: ok
Changing monitoring state from "Connecting" to "Operational"
Send: N0 M110 N0*125
Recv: ok
Send: N1 M115*39
Recv: ok