Find 2 pairs of values that behave the same

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C#3.5

I have an array that reads in e.g. 50 lines (rows) with exactly 8 columns (0...7).
Each column contain values from 0-255. I need to find 2 pairs (columns), through calculation, that behave identical (same deviation). Not necessarily the same values.

I have tried with some different math methods, but none of them works when one of the values in the columns are zero.

int[] iBit0 = new int[] { 209, 113, 161, 81, 241, 241, 81, 49, 209, 1, 81, 49, 33, 97, 129 };
        int[] iBit1 = new int[] { 30, 29, 36, 28, 29, 29, 30, 31, 29, 34, 35, 34, 34, 31, 30, 31 };
        int[] iBit2 = new int[] { 88, 97, 198, 119, 77, 87, 80, 71, 76, 84, 73, 86, 76, 70, 83, 76 };
        int[] iBit3 = new int[] { 130, 108, 130, 0, 160, 125, 215, 218, 145, 110, 0, 27, 178, 252, 169 };
        int[] iBit4 = new int[] { 30, 30, 33, 30, 29, 30, 29, 30, 29, 34, 34, 34, 34, 31, 31, 31 };
        int[] iBit5 = new int[] { 234, 74, 154, 106, 202, 202, 106, 10, 234, 58, 106, 10, 26, 90, 186 };
        int[] iBit6 = new int[] { 247, 249, 247, 246, 247, 241, 248, 249, 4, 15, 17, 29, 26, 19, 13 };
        int[] iBit7 = new int[] { 13, 19, 26, 29, 17, 15, 4, 249, 248, 241, 247, 246, 247, 249, 247 };

If I use a chart to visualize the behaviour, Bit6 & Bit7 disqualify, but Bit0 & Bit5 and Bit1 & Bit4 qualified as almost matching behaviour.

How can I be able to obtain this through calculation?

I hope someone is able to see through this plain but for me insoluble problem.

I use C# in Visual Studio 2008.

Best regards,
Lennart H.