[thxbb12]

I disagree.
This is why for certain lenses, you will see people raving about it while some people would say they suck.
It's happened and it will keep happening unless QC is very tight.
Of course, it depends on the lens model.
Lensrentals.com have shown this: a good sample of a an inferior lens could give better overall MTFs than a bad sample of a better lens.

[Brightcolours]

I disagree.
This is why for certain lenses, you will see people raving about it while some people would say they suck.
It's happened and it will keep happening unless QC is very tight.
Of course, it depends on the lens model.
Lensrentals.com have shown this: a good sample of a an inferior lens could give better overall MTFs than a bad sample of a better lens.

Lemsrentals has never said that the differences are not due to centering issues. 
So what other "QC issues" do you want to put forward?

[thxbb12]

Changing the optics to accommodate Pentax' SDM ring motor doesn't make any sense, as that is a standard "ultrasonic" ring-type motor. Those are made by various companies, it's not a Pentax exclusive.
Even more, since the Tamron already uses such a motor changing it to a "Pentax" part.... why on Earth would they do that?

Cameraville and RiceHigh? 

   
   
   I don't know if you completely read the review Kunzite ...... but it was very very comprehensive (Google translate apart) ..... and actually the reviewer was very kind to the Pentax version "throughout" ...... 
 ....... it was only at chapter 6 when comparing to the Tamron that he found differences .......

The review stated:
"At aperture F4.0, the resolution of 70mm focal length and 210mm focal length DFA is not as good as that of SP lens, but the performance of 100mm and 135mm DFA and SP are basically comparable."

  take that as you will but that is pretty much in line with Ephotozines test results (they tested and reviewed both lenses btw)  ....... and Cameraville's findings .....

  So, whether the lenses are the same or not ..... we still wait for a copy that can match the Tamron ...... 

........... sorry but the result is too messy !!
  

I disagree.
This is why for certain lenses, you will see people raving about it while some people would say they suck.
It's happened and it will keep happening unless QC is very tight.
Of course, it depends on the lens model.
Lensrentals.com have shown this: a good sample of a an inferior lens could give better overall MTFs than a bad sample of a better lens.

Lemsrentals has never said that the differences are not due to centering issues. 
So what other "QC issues" do you want to put forward?

Let me rephrase your convoluted sentence (double negations should be avoided).

You wrote:
"Lemsrentals has never said that the differences are not due to centering issues."

Which becomes, when the double negation is removed:
"Lensrentals has always said that the differences are due to centering issues."

Now, here is an lensrentals.com article that compares 25mm MFT lenses and talk quite a bit about the results of the various lenses and copy-to-copy variation:

https://www.lensrentals.com/blog/2018/01/finally-some-m43-mtf-testing-25mm-prime-lens-comparison/

I don't see them mentioning anywhere that differences are solely due to centering issues.

[Kunzite]

Changing the optics to accommodate Pentax' SDM ring motor doesn't make any sense, as that is a standard "ultrasonic" ring-type motor. Those are made by various companies, it's not a Pentax exclusive.
Even more, since the Tamron already uses such a motor changing it to a "Pentax" part.... why on Earth would they do that?

Cameraville and RiceHigh? 

   
   
   I don't know if you completely read the review Kunzite ...... but it was very very comprehensive (Google translate apart) ..... and actually the reviewer was very kind to the Pentax version "throughout" ...... 
 ....... it was only at chapter 6 when comparing to the Tamron that he found differences .......

The review stated:
"At aperture F4.0, the resolution of 70mm focal length and 210mm focal length DFA is not as good as that of SP lens, but the performance of 100mm and 135mm DFA and SP are basically comparable."

  take that as you will but that is pretty much in line with Ephotozines test results (they tested and reviewed both lenses btw)  ....... and Cameraville's findings .....

  So, whether the lenses are the same or not ..... we still wait for a copy that can match the Tamron ...... 

........... sorry but the result is too messy !!
  

The Ephotozine review actually found a drop in resolution at the longer end, 70mm being consistently very good:
https://www.ephotozine.com/article/pentax-hd-d-fa-70-210mm-f-4-ed-sdm-wr-review-34615/performance

But weren't we discussing something else?