Description:
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It is impossible put in the replacement parameter, on ereg_replace function, one literal text of this format: \digit, e.g, \1, because the substrings replacements have preference.

It, for me, is interesting when preparing string substituitions previously, with the ereg_replace function.

Reproduce code:
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echo ereg_replace("a", "\\\\0", "bbabb");

Expected result:
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bb\0bb

Actual result:
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bbabb