podman: podman rejects duplicate mount specifications

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

podman rejects duplicate mount specifications in the run command, contrary to docker

Steps to reproduce the issue:

1. $ podman run -it --rm -v $PWD:$PWD -v $PWD:$PWD fedora:30 bash

Describe the results you received:

Error: /home/avi: duplicate mount destination

Describe the results you expected:

Successful execution of the container with the mounts deduplicated

Additional information you deem important (e.g. issue happens only occasionally):

The duplicate mount specifications were generated by a script. I could deduplicate it, but I believe full command line compatibility is the goal.

Output of podman version:

podman version 1.6.1

Output of podman info --debug:

debug:
  compiler: gc
  git commit: ""
  go version: go1.12.9
  podman version: 1.6.1
host:
  BuildahVersion: 1.11.2
  CgroupVersion: v1
  Conmon:
    package: conmon-2.0.1-1.fc30.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.0.1, commit: 4346fbe0b2634b05857973bdf663598081240374'
  Distribution:
    distribution: fedora
    version: "30"
  MemFree: 4698271744
  MemTotal: 33600290816
  OCIRuntime:
    package: runc-1.0.0-93.dev.gitb9b6cc6.fc30.x86_64
    path: /usr/bin/runc
    version: |-
      runc version 1.0.0-rc8+dev
      commit: e3b4c1108f7d1bf0d09ab612ea09927d9b59b4e3
      spec: 1.0.1-dev
  SwapFree: 16869486592
  SwapTotal: 16869486592
  arch: amd64
  cpus: 8
  eventlogger: journald
  hostname: tmp.scylladb.com
  kernel: 5.2.17-200.fc30.x86_64
  os: linux
  rootless: true
  slirp4netns:
    Executable: /usr/bin/slirp4netns
    Package: slirp4netns-0.4.0-4.git19d199a.fc30.x86_64
    Version: |-
      slirp4netns version 0.4.0-beta.2
      commit: 19d199a6ca424fcf9516320a327cedad85cf4dfb
  uptime: 69h 19m 2.3s (Approximately 2.88 days)
registries:
  blocked: null
  insecure: null
  search:
  - docker.io
  - registry.fedoraproject.org
  - quay.io
  - registry.access.redhat.com
  - registry.centos.org
store:
  ConfigFile: /home/avi/.config/containers/storage.conf
  ContainerStore:
    number: 3
  GraphDriverName: overlay
  GraphOptions:
    overlay.mount_program:
      Executable: /usr/bin/fuse-overlayfs
      Package: fuse-overlayfs-0.6.3-2.0.dev.git46c0f8e.fc30.x86_64
      Version: |-
        fusermount3 version: 3.6.2
        fuse-overlayfs: version 0.6.3
        FUSE library version 3.6.2
        using FUSE kernel interface version 7.29
  GraphRoot: /home/avi/.local/share/containers/storage
  GraphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  ImageStore:
    number: 3
  RunRoot: /run/user/1000
  VolumePath: /home/avi/.local/share/containers/storage/volumes

Package info (e.g. output of rpm -q podman or apt list podman):

podman-1.6.1-2.fc30.x86_64

Additional environment details (AWS, VirtualBox, physical, etc.):

None