Have issues with 2 mitras 6100 hv's

Using a seneye reef to compare the 2 lamps there is 300 odd PAR difference between them at the surface on exactly the same settings

One lamp was bought new. Nov 2014. The other came secobdhand with a system, no idea of 2nd lamp age.

The new lamp is the master, firmware 1.17. Old lamp is slave on 1.07.

1 - would difference in firmware cause communication problems between the 2 to effect PAR this much. The naked eye can just make out the difference on the sand bed.

2 - I was thinking of old pucks but this doesn't make sense as the old lamp is giving the higher PAR.

3 - could there be a fault on the new lamp

I've been struggling with settings all last year worrying about intensities. I borrowed a seneye to get me in the ball park the after a couple of days of testing I discovered this.

It really puzzled me and has caused me a lot of problems between the 2 sides of the tank.

Please, please help. Am I missing something or just going crazy ?

Thanks