different values for periods

[shjelvan]

hello
i calculate period of a steel moment frame by eigen command and i use equalDOF command for diaphragms in 2 ways (if node 1 ,2 ,3 and 4 are in the same story level).
first way:
equalDOF 1 2 1
equalDOF 1 3 1
equalDOF 1 4 1

and second way:
equalDOF 1 2 1
equalDOF 2 3 1
equalDOF 3 4 1

the eigen command gave smaller values for periods in second way and they are closer to periods of my model in ETABS. but i see everyone use first method not the second!
why these two methods have defferent answers?and is the second way a wrong way?

[MohsenShani]

thats wrong way,

A node cannot be master and slave at the same time.