Validate Random Die Tippers
Python 2, 43 45 bytes

lambda s:reduce(lambda p,n:n*(7-p!=n!=p&gt;0),s)


43 bytes (inspired heavily by @Zgarb)

lambda s:reduce(lambda p,n:n*(p&gt;0&lt;n^p&lt;7),s)


This function combines my reduce statement with the bit-flicking logic from @Zgarb's answer, for a combination that is shorter than both.

Both answers output the following:


0 if the input is not a valid sequence
The last digit of the sequence if it is valid