I am doing a world with some community lots with seasonal decor. I use packages for my game and have run darn near all through decrapifier to slim sizes. I would like the world to export with the items so have to use packs. I have gone back and redownloaded some of the things as packs from some sites and EA.

I hope there is some way I do not have to do the lots all twice, once with the packs and once with the packages? Will the game read/default from one to the other? My guess is no, but.......................

Also, so far it seems like if I have both the pack and package of the item in my game it shows just the pack in the items?

Am I going to have to do the lots all both ways and keep copies in the library or separate world copies? Is there some easy way to do this?

If the instance IDs change in the process, they're different objects for all intents and purposes.
If you aren't getting duplicates in the catalog, it seems like the ones you have are identical.

Decrapify renumbers IDs, S3RC doesn't.
For future reference though, that isn't really what Decrapify is for. That tool fixes Sims3Packs that won't install through the launcher. You really shouldn't be using it on all of your packages, it's just mangling them.
S3RC removes encryption without the ID scramble and I believe purges thumbnail data which is why the files get smaller. Again, a very for-purpose tool and not really something to be running packages through by default.

Thank you for the info. So if some are not duplicates in catalog and are considered identical then will one default to the other if one version is removed from the game?

I've thought on it a little more (the way exported CC functions is a bit disorienting) and the tricky part seems to be however the installer determines whether someone owns the store content used in a build.
CC will be included whole, and if it's identical to CC someone already has it will overwrite just fine.
Legitimate EA Store content in a lot, however is replaced if the user doesn't also own it. While .package store content is seen as CC. I'm not sure what would take precedence!

Best case scenario, the lot 'calling' the IDs of its objects when placed will happen even after it determines the content isn't owned. Then it would appear as intended both for people with the EA content through the launcher or package. If those users' packages were renumbered the objects would be replaced, but that is more an issue package side than with your lot.
Worst case, the check for the launcher item takes priority and substitutes the items immediately.

You could make a couple of tester lots to gauge how it behaves.
Place a few s3pack items, export the lot, uninstall the items, install the lot, see if doubles appeared in catalog or if objects vanished.

Thank you for more info. I think I will have to do some testing. The only EA items I would use are ones that were freebies, but that does not mean that the person has them. And I just re-downloaded some other items to have them in pack and package versions. Also, I can test whether decrapify changes things. I know I had to do all my EA content to use as packages but may have never gotten around to do most other things as have way too much CC.