If you want to remain the Illustrator CC-CC2018 which is installed in your personal computer when updating to Illustrator CC2019, update with the following procedure. (Also FineCut/RasterLinkTools which is installed in your personal computer will be remained.)
[Procedure 1]
Click [Update All] or [Update] button at right side of Illustrator CC.
[Procedure 2]
Click [Advanced Options] button.
[Procedure 3]
Switch off [Remove old versions] of [Advanced Options] checkbox, and click [Update] button.
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