Play rate affects all blendspace samples using the same Anim Sequence
4.15 - 3450819 - YES
4.16 - 3466753 - YES
4.17 - 3502710 - YES
Result: Both samples are playing twice as fast
Expected: Each sample plays at its specified Rate Scale. If you duplicate the walk anim and set each sample as it's own AnimSequence, it will work as expected.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46560 in the post.