The same price breaks

Hello,

Can someone explain why system allows enter the same price breaks for item?

For example (Vision environment) I enter price breaks like is showed below.

Line 2 and 3 are the same. Line 1 and 2 (3) has different prices for days 20-SEP and 21-SEP. System takes price from the newest price break line.

But why system allows enter the same price breaks or the same dates for price breaks?

Thank You,

Monika