Using function like importrange \ index \ match or similar to import data to another sheet

Afternoon folks,

I am attempting to untangle a formula \ function combination that would import data from one sheet to another sheet including duplicate data...

So far I've used this

=if($A2="","",vlookup($A2,IMPORTRANGE("Sheet_URL","Sheet1!$A$2:$D$20"),2,FALSE))

But it imports only the first instance. I thought about using INDEX or MATCH but couldn't figure out how to assemble the complete formula.

Id like to use a single cell formula without resorting to a "helper column" if possible.

Included a link to a Google Sheet with a sample layout.

Thanks

docs.google.com/spreadsheets/d/1wfv5t6ybHqRopcmChXM28Nwzna2wbnA3fqbsfcW-oqk/edit?usp=sharing

VLOOKUP will only return one result, as would INDEX/MATCH. I haven't had a chance to look at your sheet yet but it sounds like you need Filter.