Two different "0" values? [duplicate]

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• Most effective way for float and double comparison 21 answers

I've this code:

if (pMorph_AuxParam_PreviousValue->mValue != value) {
    DBGMSG("test: %.12f %.12f\n", pMorph_AuxParam_PreviousValue->mValue, value);
}

but the output is:

test: 0.000000000000 0.000000000000

how is possible that two equal values are different? Some different "bits" when I place the value 0 to those var?