Bruce has a lot of data on a bunch of hard drives and he's looking for a way to catalog or collate the data, getting rid of duplicate files. Leo says there are de-duping tools that are designed to analyze and get rid of duplicates, but he'll run a risk of deleting something that only looks like a duplicate.
Adobe Lightroom has de-duping features, as does Picasa. But Leo is nervous about deleting images automatically. It's far better to just have a huge hard drive and then use Lightroom to organize his files by date. Then he can de-dupe down the road, and keep all of his RAW files. He can convert to Adobe's DNG format because it's a universal format that will always be readable.
Val wants to offload his data onto one large drive and "de-duplicate" his files. Leo says there are a number of programs that can do it, but it's something that makes him nervous because they have the potential to eliminate what it thinks is a duplicate when it isn't. A better way is to scan the contents with a redunancy check. Leo says that SyncToy is a good one.
Leo says he can keep the old drive anyway. Drives are cheap, so he could just use that as a backup.
It's not unusual to get duplicates when syncing, and Apple hasn't been particularly great with cloud services. MobileMe was a disaster and iCloud has it's issues too. Since Julie is syncing multiple devices, it's possible that iCloud isn't merging the entries from each device into one contact. Unfortunately, the only real way to fix this is for Julie to pick one of the entries and manually delete the others. It's also important to turn off iTunes syncing after turning on iCloud syncing. Using both will cause duplication also.
Yes, iTunes Match will mark songs as duplicate and will not re-upload them. After buying iTunes Match for $24.99, he can delete his songs & re-download them. Not only will he get the higher quality versions of his songs, they will also be free of the duplicates.
It's also still possible to show duplicates in iTunes in the "File" menu, but that can be difficult to work with.