Broken: 2.77a abf6f08
The MDD exporter inserts a dummy frame at the start of the exported data. This undesirably duplicates the first frame and pushes the actual ending frame data past the official end of the MDD file. You can spot this by comparing the actual exported MDD data size with the expected MDD data size of 4 bytes * (1 + 1 + framecount + 3 * framecount * pointcount).
The MDD exporter also does not allow exporting starting at frame 0, while the importer does allow so (that one even allows starting frame -300000).