Email appear 3 times in _subscriptions_queue

Hi,

Should it be possible for an email to appear more than once in _subscriptions_queue?

My client has been noting that she has been getting the email from Subscribe by Email more than once every time. I just checked _subscriptions_queue and found that her email appeared 3 times.

Is that normal? Or a possible plugin bug?

Ps. Please note that the email only appears one time if I search for it in the back-end.

Sincerely,
Mika