ARTFUL

starting with all zstd packages installed:
ii  libzstd-dev                                1.3.1+dfsg-1                                 amd64        fast lossless compression algorithm -- development files
ii  libzstd1                                   1.3.1+dfsg-1                                 amd64        fast lossless compression algorithm
ii  zstd                                       1.3.1+dfsg-1                                 amd64        fast lossless compression algorithm -- CLI tool


dist-upgrade:
The following packages will be upgraded:
  libzstd-dev libzstd1 zstd
3 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


results in:
ii  libzstd-dev                                1.3.1+dfsg-1ubuntu0.1~ppa2                   amd64        fast lossless compression algorithm -- development files
ii  libzstd1                                   1.3.1+dfsg-1ubuntu0.1~ppa2                   amd64        fast lossless compression algorithm
ii  zstd                                       1.3.1+dfsg-1ubuntu0.1~ppa2                   amd64        fast lossless compression algorithm -- CLI tool

installing libzstd1-dev:
The following NEW packages will be installed:
  libzstd1-dev
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.


removing libzstd-dev also removes libzstd1-dev:
The following packages will be REMOVED:
  libzstd-dev* libzstd1-dev*
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.


installing just the new libzstd1-dev:
The following additional packages will be installed:
  libzstd-dev libzstd1
The following NEW packages will be installed:
  libzstd-dev libzstd1 libzstd1-dev
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.