So far I know, this should not happen as pipedrive treats organizations as separate entities. If this happen, pipedrive will treat them as duplicites as it compares name and adress of organisations
Pipedrive should not use information from last entry. If yoh have mutiple branches I find it best to import the data, it is faster and cleaner.
@Steve Kearney we'll always show you possible duplicates when creating a new org but we'll never pre-fill the data unless you manually select an option we show you once you start typing. Down here are two examples of how it looks like: