Email Checked Invoices not recorded

[itsa]

I used "Email Checked Invoices" and selected 4 or 5 to send in batch but they were not being recorded as Emailed. I re-sent them one at a time and they got "Emailed". Now I am not sure if the customer received 2 copies of the same invoice.

Is something wrong with the "Email Checked Invoices" ?

Thanks