Import mixes JPG and HEIC purely on filename, moving old images to new locations on disk

When filenames with old pictures (JPG) and new (HEIC) collide, on import LR moves the old picture to the new folder, even though EXIF data clearly has completely different date and time, and the pictures are completely different. 

Scenario to replicate is in two parts. 

Part 1. 

• There are pictures imported from old iPhone where the compatibility setting was on (converting image from HEIC to JPG automatically on import). 
• From the old iPhone a picture was imported with rolling counter such as for example IMG_5533.JPG. The file is located as (say) Lightroom library/2016/09/29/IMG_5533.JPG on disk.
• All good. Everything is as expected.

Part 2. 

• A new iPhone was taken into use, which started its rolling counter from beginning.
• From the new iPhone a picture was imported with rolling counter such as for example IMG_5533.HEIC, matching the filename except for the extension part. The file is located in (say) Lightroom library/2023/05/03 folder on disk.
• When LR imports IMG_5533.HEIC, it also moves the Lightroom library/2016/09/29/IMG_5533.JPG to the same folder as the .HEIC, i.e. Lightroom library/2023/05/03/
• EXIF data on the HEIC and JPG are different and the pictures are different. 
• LR incorrectly makes an assumption based on the filename part and incorrectly moves the file.