i suspect it’s inadvertent.
you might try seeing how many bytes are contained in the file; and then see if that run of file names is outside that span. or, if it seems within the size of the expected file:
you might try putting a bunch of unnecessary data (shapes, whatever) in your draft, saving, then deleting that cruft, then saving again, and then view the file.
re: 1. potentially, it could be previous data from something previously written to disk. the whole, write zeros to a hard drive to make the data unrecoverable thing.
re: 2. this is really an expansion of 1. draftsight might ask for a file of a certain size, maybe using a memory mapped file, and may only be writing to a small chunk of that space to save your draft. ( that sort of thing is sometimes done for fast file access if its known the files are going to get really large. ) in asking for a big chunk up front, it may get some recycled data off your drive.
some things i trawled up in a super quick search:
it looks like dwg is the autocad binary format.
the ac1027 ( first bytes in your pic ) indicate the autocad 2013 format.
that’s probably the one draftsight either reverse engineered or used some library for. so it probably wouldn’t be them doing anything on purpose.
there’s an “open design” [document (pdf)] describing (https://www.opendesign.com/files/guestdownloads/OpenDesign_Specification_for_.dwg_files.pdf) some of the content. section 3 ( page 20 ) “r12-r15 dwg file format organization” starts the more interesting bits.
my first guess would have been it stores some sort of zip-like filesystem; but a quick look at the format seems to say no. so see the other theories above.