Orders coming through separatley

[purplegiants]

Hi,

 

Im running PS 1.6.1.4

 

When i get an order from a customer they often come through as a separate orders with the same order number.

 

Example customer A orders £40 worth of goods

 

I get a notification of 2 orders

1 for £19

1 for £21

 

Why is this and how can i stop it?

 

Thanks