Is there a way to copy data from one application to another application On Edit the record entry?

e.g. I have two applications, 

1) New Stock. [form name = Invoices] 

2) Old Stock [form name = Invoices]

Note: All fields are same in both application forms.

I am going to edit the record and doing some modifications in "New Stock" app. When click on update button, I want to copy that record to the "Old Stock" application. Is that possible?

FYI: In modification process, there may be some conditions, if matches than record will copy to the new application, if doesn't match, only update will occur. 

Sorry for poor English.