how do you tell what generation a bulldog knife is ?

[gregchampion]

how do you tell what generation a bulldog knife is

 

[kvaughn]

The old ones have two dogs fighting, the new ones only show one dog.--KV

 

[T. Scott]

I have one here now that has two dog heads etched on the main blade and also two dog heads on the tang. I have no idea what era it is.