It´s quite simple (although slightly speculative), Ian.
The Haruta Ietsugu, we are (all?) refer to, is said, signed with three diffrent mei:
„Bishû-jû Yamato Ietsugu“ (尾州住大和家次), the one from the MET!
„Nanto no jû Haruta Ietsugu“ (南都之住春田家次)
and
„Yamato no Kami Fujiwara Ietsugu“ (大和守藤原家次), as I posted above!
Unfortunately, Sasama is a bit vague in his classification.....and that seems exactly the problem. All expressed opinions here are (more or less) based on one source, Sasama`s "Shin Katchushi Meikan". The rest is made up by personal views supported by alignments of circumstancial evidence.
Well, we know that this strained source, is sometimes not completely trustworthy. So actually, we have to live with the current situation, that nobody can provide a real proof for what he claimed. But we can try to narrow down the possibilities until we find an adequate specimen for reference!
Dave, as a katchushi, whats your opinion?