Error when trying to run orch command if another orch is running by scheduler.

Description of Issue/Question

I have two orchestration state files. First one is running every 15 minutes by scheduler:

schedule:
  http_frontend_haproxy:
    function: state.orchestrate
    minutes: 15
    args:
      - orch.http_frontend.haproxy

/srv/salt/orch/http_frontend/haproxy.sls:

orch_haproxy_conf_generate:
  salt.state:
    - tgt: 'config_server'
    - sls: 
      - orch.http_frontend.haproxy_conf_generate
   
orch_haproxy_conf_update:
  salt.state:
    - tgt: 'role:http_frontend'
    - tgt_type: 'grain'
    - sls: 
      - orch.http_frontend.haproxy_conf_update

And second one I'm running manually with command:

salt-run state.orch orch.http_frontend.bird

/srv/salt/orch/http_frontend/bird.sls:

refresh_pillar:
  salt.function:
   - name: saltutil.refresh_pillar
   - tgt: 'role:http_frontend'
   - tgt_type: 'grain'

update_bird_config:
  salt.state:
    - tgt: 'role:http_frontend'
    - tgt_type: 'grain'
    - sls: 
      - http_frontend.bird_config

If first orchestration is already running by scheduler and I'm trying to run second one with salt-run state.orch - I'm getting error:

master:
    Data failed to compile:
----------
    The function "state.orchestrate" is running as PID 16907 and was started at 2016, Nov 30 18:18:56.071485 with jid 20161130181856071485

But everything is fine if I'm running both of them manually with commands:

salt-run state.orch orch.http_frontend.haproxy
salt-run state.orch orch.http_frontend.bird

What am I doing wrong?

Versions Report

Salt Version:
Salt: 2016.11.0

Dependency Versions:
cffi: Not Installed
cherrypy: 3.2.2
dateutil: Not Installed
gitdb: 0.6.4
gitpython: 1.0.1
ioflo: Not Installed
Jinja2: 2.7.2
libgit2: Not Installed
libnacl: 1.4.3
M2Crypto: Not Installed
Mako: Not Installed
msgpack-pure: Not Installed
msgpack-python: 0.4.8
mysql-python: 1.2.3
pycparser: Not Installed
pycrypto: 2.6.1
pygit2: Not Installed
Python: 2.7.5 (default, Nov 20 2015, 02:00:19)
python-gnupg: Not Installed
PyYAML: 3.11
PyZMQ: 15.3.0
RAET: Not Installed
smmap: 0.9.0
timelib: Not Installed
Tornado: 4.2.1
ZMQ: 4.1.4

System Versions:
dist: centos 7.2.1511 Core
machine: x86_64
release: 3.10.0-327.28.2.el7.x86_64
system: Linux
version: CentOS Linux 7.2.1511 Core

Reproduce the conflict using the scheduled state.orchestrate job and the manual salt-run state.orch commands shown in the report. Start by tracing the state.orchestrate execution and its running-process check, then compare it with two manually launched orchestrations. Done should be defined as the intended behavior for concurrent orchestrations and covered by a regression test.