A zip file is supposed to be able to reproduce the contents exactly.
One related note though -- it is more difficult to recover the data if a zip file gets corrupt, than if the data was in the original format. Why? Many file formats have built in redundancy, and are designed so that either minor errors are correctable, or minor errors are not critical.
Imagine a video file. In most formats, if a small portion gets corrupt, you will see a temporary flicker in that small portion of the video but can still watch the video. But if the video file is zipped, the error correction capability is reduced, and depending on the extent of corruption, you simply may not be able to unzip the file / watch the video. (This is contrived example as it is useless to zip most video formats in any case).
This is true for any compression format - compression by definition reduces reduncancy and hence error correction capabilities and its a trade-off.