vinyl jambliner with offset channels

A contractor from Los Angeles, CA says:
Hi Swisco, I am stumped. Have you ever seen a jamb liner where the two channels are not on an even plane (or level) with each other? I have liners where the channel for the upper sash is 1/8" offset from the lower sash channel, which means that the upper sash is overall 1/4" narrower than the lower. The sashes and/or liners do not indicate a brand and I am just curious if you have ever heard of this?

User submitted a photo of window hardware.
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Paul from SWISCO responded:
Hello, Scott. I have actually never noticed this before . I believe your channels were made that way for tilting purposes, or perhaps one sash is thicker than the other because of weather stripping.
A contractor from Los Angeles says:
Hi Paul, my thoughts too. It was probably that the upper sash had a form of weatherstripping on the edge of the sash that the manufacturer worried would be torn off while tilting the upper sash in past the lower sash's jamb liner channel. These liners date back to the very early days of jambliners and may reflect a worry that later experience showed to be unfounded. Who knows?

The shame is, now I can only repair this window if I laminate on a thin strip of lumber to the edges of the upper sash, re-bore the edges and then change the jamb liners to the traditional level-type. It will end up being too much money in carpentry to warrant avoiding a new window install.

So any guess as to who may have been the mfg'er?

Thanks again,
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Paul from SWISCO responded:
I'm not sure. Are there any AMAA stickers on the inside of the frame or sash? If you show me that, I may be able to deduce who made it.
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