I maintain linuxsampler-svn on the Arch User Repository and I got a bug report that linuxsampler-svn conflicts with nilfs-utils. The problem is lscp, because nilfs-utils contains a tool that is named exactly the same. It looks like nilfs-tools had lscp first, so I would suggest that you rename lscp to lscpsh to avoid the conflicts. I guess arch is probably not the only distro affected by this.
What is the other "lscp" application doing actually?
I don't use it myself but this page http://nilfs.sourceforge.net/ja/man1/lscp.1.html says it's used to list nilfs checkpoints.
To make it short: I suggest you rather handle this with a patch in your package in a way that you feel would be appropriate for your distribution now.
As far as I can see it, even though LinuxSampler might not be a mainstream application, the mentioned NILFS file system isn't a widely popular one either (yet). I would say chances are actually low right now, that more than few couple users would install both of them at the same time.
Regarding the "he was first" reason: LinuxSampler exists since 2002. So it's five years older than NILFS. And the "lscp" terminal application has a similar importance for LinuxSampler, as "psql" has for PostgreSQL.
That does not mean that I am definitely opposed to renaming "lscp" to something else on the mid / long term, but ATM the reasons you gave do not seem to be significant high enough for me to actually rename the "lscp" application to something else.
Regarding other distributions: yes, there are also other distributions which would have the same problem. Considering how many software packages there are in today's distributions, there are indeed quite some amount of package with similar conflicts in all distributions. And usually they are addressed by package maintainers first. And only if one of the conflicting packages reached a high significance over the other one in public eye, then it would usually be addressed upstream. But I don't see this to be the case (yet).