Slippage Tab Reliability

 

How reliable is the slippage tab in a signals?

There are some servers that show higher slippage, but for example Alpari2 and Alpari3 have a 4 seconds of difference in the slippage, but an Alpari Rep told me that it is "almost" the same server, so shouldn't it be the same slippage?

How reliable is this and how is it calculated?

Thanks. 

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