Thomas, The simple answer is that someone rebuilt it the way they knew how to rebuild one with the c-clips. No matter why or how, the bearing needs to be trapped without using a seal as part of the 'stack'. I know this from extensive training and experience with bearings. Even if it were original to the housing you could do a great improvement by getting that seal out of the bearing stack.
Add: There is only one remote possibility that this stack could work the way it is and that would be that the seal is not your normal seal. If the seal is beefed up enough to pass as a spacer it could work. If it's made of your normal sheet metal then it wouldn't have enough structure to hold the bearing in place like it should.
