Do old 2 prong outlets have line/load separation?
Normal receptacles don't have "line" and "load".  That is not a thing.  That concept is only associated with GFCI and AFCI where the "Load" provides a protected zone to additional outlets (that are properly wired).  

On a normal receptacle of any vintage, the dual side screws are simply a convenient splicing feature to allow two wires to be spliced to each other and also to the receptacle.  

It is more compact than a 3-wire pigtail, for instance.  You are welcome to use that, the pigtail or any splicing method you please.  All do the exact same thing and are interchangeable.*  

On newer receptacles, you can delete the "convenient splicing feature" and exchange it for the ability to feed each socket independently.  This is done by breaking off special "tabs" that jumper the screws together.  When changing receptacles you must check for broken tabs, that is the #1 mistake. 



* A few situations, such as MWBC, require a pigtail or other scheme that lets you remove the receptacle without breaking the supply wire to downstream outlets. In those cases, using the receptacle as the splice is outlawed.