The two different software collections that both ship .NET Core 2.x include different versions of incompatible files for bash completion. Both need to install the bash completion file to /usr/share/bash-completion/completions/dotnet. This is not an SCL-specific path, but a general system path. To make this work, both SCLs need to ship an identical copy of this file. Otherwise it's not possible to install them both side-by-size. Thankfully, this is easy enough to fix: we can just take the latest bash completion file from upstream and make sure both SCLs use the exact same file. There haven't been any backwards-incompatible changes to this file in the last few years: https://github.com/dotnet/cli/commits/master/scripts/register-completions.bash (As a bonus, the latest upstream version of the bash completion file contains additional fixes we pushed to fix some issues)
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2019:1236