Unable to register extension

Hi,
I have an asterisk v1.6.2.13 (from the atrpms repo) system and I believe it’s working okay. I’m receiving the following warnings in my logs and I’m unsure how to troubleshoot this:

[Mar 25 19:50:15] WARNING[10280] pbx.c: Unable to register extension '_X', priority 1 in 'mainmenu-night', already in use [Mar 25 19:50:15] WARNING[10280] pbx.c: Unable to register extension 's', priority 2 in 'incoming-sales', already in use

There are two warnings for two different sections, but I’d like to just focus on the first one for now. This is the section from extensions.conf for mainmenu-night that the error is referencing:

[mainmenu-night]
exten           => _1NXXNXXXXXX,1,Answer
exten           => _1NXXNXXXXXX,2,Ringing
exten           => _1NXXNXXXXXX,3,Wait(3)
exten           => _1NXXNXXXXXX,4,Set(TIMEOUT(digit)=2)
exten           => _1NXXNXXXXXX,5,Background(local-mainmenu-night)
exten           => _1NXXNXXXXXX,6,Wait(1)
exten           => _1NXXNXXXXXX,7,Ringing
exten           => _1NXXNXXXXXX,8,Wait(2)
exten           => _1NXXNXXXXXX,9,Voicemail(7111@local,u)
exten           => _1NXXNXXXXXX,10,Hangup
exten           =>   1,1,Goto(support-auth,s,1)
exten           =>   9,1,Set(CALLERID(all)=9 - ${CALLERID(name)} <${CALLERID(num)}>)
exten           =>   9,2,Directory(local)
exten           =>   9,3,Hangup
exten           => *86,1,Goto(local,*86,1)
exten           =>  _X,1,Playback(invalid)
exten           =>  _X,1,Goto(incoming,s,1)
exten           =>  _X,2,Goto(incoming,s,1)
exten           => h,1,Hangup
exten           => i,1,Hangup
exten           => t,1,Hangup

I inherited this configuration, and it was converted from an older asterisk v1.2 and it worked without issue. Now I’d just like to make sure that this warning isn’t causing a problem and to try and understand why it’s happening.

Thanks,
Alex

exten           =>  _X,1,Playback(invalid)
exten           =>  _X,1,Goto(incoming,s,1)

two lines with the same pattern and priority.