No.
The star database in v1.6 is updated since the v1.5 series: it is based on the
2007 reduction of the Hipparcos data by Floor van Leeuwen so the parallaxes presented should be more accurate than those in previous versions of Celestia. The number of stars actually included is similar to the default v1.5 databases (actually there are slightly fewer due to more rigorous conditions for excluding stars with dubious parallaxes from the database).
While Pascal Hartmann's star databases do contain more stars, the positions are less accurate and based on older reductions of the data. You should consider whether this is a tradeoff you are willing to make if you use them with v1.6.