Can a lower T8 outperform a higher T12 ?

[SL3]

It seems my T8 5000k 2850 lumens are out performing my T12 6500K 2900 lumens. Is that possible? 
 
I started slowly changing from T12 to T8s for my starters as an experiment, but thought I might lose some overall growth in my seedlings at the lower wattage and less lumens. But I have to say the plants under the T8’s seem to be growing better and at a faster rate. Does this make sense?

 

[Weed]

Isnt T-8 newer than T-12?
 
One thing that might explain it is the age of the bulbs. Otherwise I dont think youd notice the difference 50 lumens makes in growth.