Are these bricks old LEGO/Duplo clones? Can anyone identify these bricks, which I suspect are LEGO clones.  They may be more than 30 years old.
I bought them on ebay as Betta Bilda from LEGO/Duplo dealer. Some BB was included, but these are unknown to me, with an extensive BB collection.


The underside of the bricks is hollow and with apparently random numbers - they aren't part numbers because they are different for the same part and sometimes the same for different parts.  Window frames have no top studs.



I took a good look through many posts with similar questions, but found nothing that matched.  Many Google reverse images searches kept pointing at real LEGO/Duplo, before I noticed this place.
Usually I can identify unknowns like this, but these are a real challenge.
Edit (Nov 29, 2019)
Some comments have asked for clarity on size of these bricks.  The majority are close to if not identical to 8 stud LEGO, although there are also 2 and 4 stud bricks too.  They clip to Betta Bilda pieces, in a similar way to authentic LEGO. The window frames appear to be confirmed by two comments as 1950-60 LEGO, but additional insight would still be appreciated.
As suggested by @mindstormsboi I contacted LEGO customer services and sent them a link to this question as well as many additional photos.  The information was passed to their expert team and the answer that came back was &quot;they believe that these are not LEGO® parts&quot;. They were not able to identify them as a known clone type. I feel obliged to accept that as a definite answer, although it leaves unknown who actually manufactured the bricks I have.  I will continue research into that question, but elsewhere.
The customer service team member also gave me two interesting links to a fan created website with some of the history of LEGO parts, as well as section covering many of the clones and similar brick building sets.  I include the two links below, as they may be of interest to some who find this question and answer.
https://www.inverso.pt/legos/
https://www.inverso.pt/legos/clones/texts/mobitec.htm
Thank you to all who contributed their knowledge, experience or point of view.