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The additional point is found with Sage version 7.5.rc2 so will be there in the next release. There was a bug fix since 7.4. However the MW basis used is the same in each case, with regulator 5.695... and this is also what mwrank gives, with a claim that the given points are saturated. I also just checked by hand that the generators are OK.

I think that your diagnosis was put off by a misleading message printed with verbose=True: the curve has 2 real components and there are rational points on the non-identity component (the "egg"). In the algorithm, the first step is to replace the full MW basis with a basis for the index 2 subgroup $E(\mathbb{Q})\cap E^0(\mathbb{R}}$, but this is allowed for later.

In fact the bug was quite different, and due to a precision problem which has been fixed.