Issue 834195  has been merged into this issue.
 Issue 834196  has been merged into this issue.
 Issue 834197  has been merged into this issue.

I've noticed that this does not happen on luci-milo-dev server, so seems like this might have been fixed on ToT. Leaving this open until that is verified though.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/luci/luci-go.git/+/0706732375aa6620c952dcb0d124f64221b7a09c

commit 0706732375aa6620c952dcb0d124f64221b7a09c
Author: Ryan Tseng <hinoka@google.com>
Date: Fri Apr 20 22:09:20 2018

[milo] Fix duplicate builders in console

Bug:  834198 
Change-Id: I33596cf7ff39be01fd0b50c1b50d82f06f820383
Reviewed-on: https://chromium-review.googlesource.com/1020286
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Commit-Queue: Ryan Tseng <hinoka@chromium.org>

[modify] https://crrev.com/0706732375aa6620c952dcb0d124f64221b7a09c/milo/common/config.go

I've verified that this was fixed in the latest revision, which I've just deployed.