Don't see this as having been mentioned yet so...
There appears to be the same book in both Logos *and* Faithlife eBooks.
The Natural Sciences: A Student’s Guide (Logos)
The Natural Sciences: A Student's Guide (Faithlife)
Obviously the Logos one is the better deal.
FL does not intend to sell both a FLEB and Logos edition of any given resource, but they do not have an automated method to weed them out. The FLEB title will be pulled as soon as FL realizes this.
Most of the time when this happens, the FLEB title is cheaper and you should grab it quickly. [:)]