Interesting what you & others say & not surprising to me. I recently went through this kind of exercise looking for Blu Helvetia (Swiss blue),
which was later re-named Blu Francia :French blue. The number of Alfa blues I found across different paint manufacturers was quite staggering & I had NO idea there were so many across the years. I would say around 6 different blues in that mid to light range which people might call Le Mans blue. Also the same I.D. code number can appear quite different from paint maker to maker, & or the mix recipes for a particular code are so different, the results cannot ever come out the same across makers anyway.
In the end we ignored the different code mixes from Max Meyer, Glasurit, Lesonal etc, and mixed to a color sample from inside the fuel flap.
So, I would say if you don't have the paint makers label & code sticker, you probably don't have much chance of getting it right. Better to match from a sample. But I do understand that you car is already painted & you just want to know the color, so my best guess is it's a mix version of another paint maker other than the original paint inside your boot, or an anomaly of the modern paint tints which DO NOT seem to come up correct to the original color sample anyway. A certain amount of extra adjusting seems necessary with modern paints.
regards,
Vince.