DOES MAN MADE CO2 HAVE SPECIAL PROPERTIES?

I have not read that some scientists believe that "man made" CO2 has a longer atmospheric life-time than other CO2 until this report referenced it. 

New Study Rebuts The Assumption That Anthropogenic CO2 Molecules Have ‘Special’ Properties

As a scientist myself I do not believe there is any evidence that any CO2 molecules have different physical properties from any others. I have read that some believe that the life-time of CO2 from any source in the atmosphere is much longer than the 4 years that was previously accepted. The arguments for the longer time is not convincing to me.