Email sending scripts running twice

My RT instance has started duplicating emails sometimes:

Nov 20 14:58:54 rt RT: [24380] rt-4.4.0-24380-1542747534-856.8967-5-0@example.com #8967/313500 - Scrip 5 On Correspond Notify Requestors and Ccs
Nov 20 14:58:54 rt RT: [24380] rt-4.4.0-24380-1542747534-856.8967-5-0@example.com sent To: XXXXX@example.com
Nov 20 14:58:54 rt RT: [24380] rt-4.4.0-24380-1542747534-1490.8967-43-0@example.com #8967/313500 - Scrip 43 On Correspond Notify Windows Admins if Unowned
Nov 20 14:58:55 rt RT: [24380] rt-4.4.0-24380-1542747534-1490.8967-43-0@example.com sent To: AAAAA@example.com, BBBB@example.com, CCCC@example.com, DDDD@example.com, EEEE@example.com, FFFF@example.com

Nov 20 14:58:55 rt RT: [24379] rt-4.4.0-24379-1542747535-435.8967-5-0@example.com #8967/313503 - Scrip 5 On Correspond Notify Requestors and Ccs
Nov 20 14:58:55 rt RT: [24379] rt-4.4.0-24379-1542747535-435.8967-5-0@example.com sent To: XXXX@example.com
Nov 20 14:58:55 rt RT: [24379] rt-4.4.0-24379-1542747535-852.8967-43-0@example.com #8967/313503 - Scrip 43 On Correspond Notify Windows Admins if Unowned
Nov 20 14:58:55 rt RT: [24379] rt-4.4.0-24379-1542747535-852.8967-43-0@example.com sent To: AAAAA@example.com, BBBB@example.com, CCCC@example.com, DDDD@example.com, EEEE@example.com, FFFF@example.com

I recently made a big change away from using AdminCCs as queue watchers to use custom scrips & NotifyGroup custom actions for each queue. However, it’s not just the new custom scrips that are firing twice, it’s also the unmodified default scrips (like #5).

It only happens sometimes, but it’s super annoying and unprofessional when it replies twice to our users.

I’m running 4.4.0 (yeah it’s in need of an upgrade, but didn’t see anything in the patch notes for any of the updates that addressed this sort of thing) on CentOS 6.

I’d found a couple other threads that seemed to be similar problems but they mostly concerned the stage at which scrips ran? But I can’t see how that’d be affecting the default ones.

Any help or pointers would be appreciated, I can’t figure out what’s going on.