About shipping setting

[yoami]

When I set the freight rate for all countries over $50 free freight, less than $50 charged $5 freight as below:

However, when I tested order two products, but the total amount was less than $50, it showed that the freight charges double $5 ,Total $10 freight charges, As below:

Can you tell me how to set up a shipping charge is $5 for orders less than $50, Nomatter how many orders are placed .

Thanks and waiting for your reply

Best Regs

Yoami