I know that when I file a patent application, a research will be done on novelty. This research covers (theoretically) all known publications, existing patents and applications up to the date of filing.
However, does it also includes patent applications that are yet unpublished? I assume not, because then an inventor gets notified of unpublished patents.
But does this imply that an inventor can file multiple applications that are based on the same innovative thought? For example: suppose I invented a new type of measurement system and filed a patent application. After a couple of months I discovered an even further improved system that is not covered by the "old" application. Filing a new one may be rejected because technically it only differs a little. But if the old application is not included in the research it will not pose a problem.