when used with multiple repositories and two repositories have the same package, slackpkg show only the first (in the order specified in PRIORITY & PRIORITYPLUS configuration).
when one repository contains multiple packages with same name (some repository contains both 32 and 64 bit architectures and/or multiple slackware version, 14.0, 13.37, 13.1 ...), slackpkg show only one package, in a unknown order!! An example is the AlienBob repository.
slackpkg+ try to detect the best package for your installed slackware, but it may fails!