Help with Topps !! Gold or Bronze ?

I've never seen anything written on this, but I'm pretty sure there probably has been.

Has anyone ever noticed a difference in 1993 Topps Gold cards ?

I have three Indian cards that seem more bronze than gold.

 

 

Here's the "normal" gold.

 

 

Here's the "bronze".

 

 

You can easily see the difference and it's not  just the way the light hits the cards.

 

 

 

I'm guessing this is just some sort of production variance.

 

Does anyone know anything about this ?