[freeside-users] Export Error with FS 1.5.8

[webmaster]

Dear freeside users,
I’m using Freeside 1.5.8, I created a “shellcommands – Real-time export via remote SSH”
 with the following properties:

Insert command: /bin/testInsert
Delete command: /bin/testDelete
Modify command: /bin/testModify

I assigned this export to a service then to a package.
The problem is: when a user buys this package, the Freeside system calls the
 Insert command (calling /bin/testInsert) and Modify command (calling /bin/testModify)
 at the same time! Instead of calling the insert command only!
Why this error appears, is this a bug?
Thanks for your help
Sameh Fakoua