What makes a double pumper a double pumper?

Thanks guys, I figured it was something like that, just couldn't figure out why they would have squirters for the secondarys.

How about these newer carbs like the Holley street avenger, or the Quick fuel SS680, both these are available in manual or vacuum secondary's , but are these double pumpers or do they just look like it because of the duel fuel line feeds? Considering one of these two for my 5.9 swap.

Holley Street Avengers are available with vacuum secondaries only, and have 1 accelerator pump (primary side).

Straight from Holley's web site-
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