If you mxCompare(m1, m1) a model with itself, you get the warning
In collectStatistics(nextBaseSummary, nextCompareSummary) :
Model 'exampleModel' has more degrees of freedom than exampleModel which means that either the models need to be compared in the oppposite order or the models are not nested and should not be compared with the likelihood ratio test
Neither model has more degrees of freedom than the other. Perhaps just give the comparison without a warning?