Aperture --> Lr

Hello All-

I am going to officially convert from Aperture to Lightroom and need an answer to a question...

Somehow, someway, I ended up with 2 Aperture Bundles/Libraries.  There is a 15 gig difference between the two libraries.  I have no idea how this happened but it has.  My question is:

If I convert/import the 1st library and then convert/import the 2nd library will Lightroom, during the conversion process, recognize any and all duplicates between the two libraries and discard the duplicates during the conversion process of the 2nd library?

I am certain there is major, major overlap between the two libraries and we are talking thousands and thousand of pictures.  I don't want to convert the 1st library, then the 2nd library and end up with a final Lightroom library with 1,000's of duplicates to clean up.

One final question, if I want to include pictures from Photos app to create a "unified", "single" library; having Lightroom be the single repository of all previous and future photos does anyone have any suggestions for that?

Basically, I want one library for ALL photos from the past and want to use Lightroom as the ONLY repository for ALL photos going forward.  I realize this is probably going to be an onerous task.  I just want to make sure I do it right the first time.

If anyone out there can answer these questions I would be extremely grateful.  Also, if anyone out there has any tips, pointers, suggestions for the conversion process I would love to hear.  Thank you SO much!