Quick fix:
$ ssh login.tools.wmflabs.org $ become bridgebot $ bb.sh restart 'Double IRC messages to other bridges'
This has been seen several times now: 2022-03-22, 2022-04-04, 2022-04-05. Things are going along fine and then something happens which makes the bot start outputting double messages from IRC source channels to Telegram sink channels.
Related upstream issue: Duplicate messages when bridging IRC/ZNC to Telegram after some days #1564
Logs grabbed during the 2022-04-05 occurrence hint that the bot got disconnected from it's ZNC bouncer and when it reconnected it is receiving 2 copies of each message:
time="2022-04-05T12:14:45Z" level=debug msg="<= Sending message from * on irc.libera-bridgebot to gateway" func=handlePrivMsg file="bridge/irc/handlers.go:240" prefix=irc
time="2022-04-05T12:14:47Z" level=error msg="Connection is not alive: &model.App Error{Id:"api.context.session_expired.app_error", Message:"Invalid or expired session, please login again.", DetailedError:"", RequestId:"37xqyp9hd3nozmtzepmy3c7gmh", StatusCode:401, Where:"", IsOAuth:false, params:map[string]interface {}(nil)}" prefix=matterclient
time="2022-04-05T12:14:52Z" level=error msg="error:read tcp 192.168.222.129:35490->172.16.5.238:443: use of closed network connection" prefix=matterclient
time="2022-04-05T12:14:52Z" level=info msg="Found version 5.27.0.5.27.0.db2087c7e98dbb848bfc441d46ca3a0d.false" prefix=matterclient
time="2022-04-05T12:14:52Z" level=debug msg="Registering callbacks" func=handleNewConnection file="bridge/irc/handlers.go:121" prefix=irc
time="2022-04-05T12:14:53Z" level=info msg="found 640 users in team wikimedia" prefix=matterclient
time="2022-04-05T12:14:57Z" level=error msg="error:websocket: close 1006 (abnormal closure): unexpected EOF" prefix=matterclient
time="2022-04-05T12:14:58Z" level=debug msg="handle girc.Event{Source:(*girc.Source)(0xc001332f30), Tags:girc.Tags{"time":"2022-04-05T12:14:58.906Z"}, Timestamp
:time.Date(2022, time.April, 5, 12, 14, 58, 906000000, time.Local), Command:"JOIN", Params:[]string{"#wikipedia-es-wikiproyectos", "wm-bridgebot", "https://wikitech.wikimedia.org/wiki/Tool:Bridgebot"}, Sensitive:false, Echo:false}" func=handleJoinPart file="bridge/irc/handlers.go:117" prefix=irc
...snip...
time="2022-04-05T12:14:58Z" level=debug msg="333: Topic set by hare [sid388306@user/hare] [2021-06-16 01:01:08 +0000 UTC]" func=handleTopicWhoTime file="bridge/irc/handlers.go:263" prefix=irc
time="2022-04-05T12:14:58Z" level=debug msg="333: Topic set by hare [sid388306@user/hare] [2021-06-16 01:01:08 +0000 UTC]" func=handleTopicWhoTime file="bridge/irc/handlers.go:263" prefix=irc