title: How to use bluetoothctl like hcitool lescan to report repeated proximity beacons
body: <p>I can use hcitool lescan with the --duplicates flag to capture periodic LE Advertising Reports (proximity beacons) from two nearby BLE devices:</p>
  
  <pre><code>$ sudo hcitool lescan --duplicates
  LE Scan ...
  C8:0F:10:29:4D:98 MI1S
  C8:0F:10:29:4E:75 MI1S
  C8:0F:10:29:4E:75 MI1S
  C8:0F:10:29:4D:98 MI1S
  C8:0F:10:29:4E:75 MI1S
  C8:0F:10:29:4D:98 MI1S
  &lt;snip&gt;
  </code></pre>
  
  <p>Here is that scan again, with timestamps added to show the periodicity:</p>
  
  <pre><code>$ sudo stdbuf -i0 -o0 -e0 hcitool lescan --duplicates | perl -nle 'print scalar(localtime), " ", $_'
  Wed Apr 13 13:46:45 2016 LE Scan ...
  Wed Apr 13 13:46:46 2016 C8:0F:10:29:4E:75 MI1S
  Wed Apr 13 13:46:47 2016 C8:0F:10:29:4D:98 MI1S
  Wed Apr 13 13:46:48 2016 C8:0F:10:29:4E:75 MI1S
  Wed Apr 13 13:46:48 2016 C8:0F:10:29:4D:98 MI1S
  Wed Apr 13 13:46:50 2016 C8:0F:10:29:4D:98 MI1S
  Wed Apr 13 13:46:52 2016 C8:0F:10:29:4E:75 MI1S
  &lt;snip&gt;
  </code></pre>
  
  <p>At the Embedded Linux Conference and IoT Summit last week (April 2016), a presenter who works on the BlueZ stack said to no longer use hcitool, and to use bluetoothctl instead.</p>
  
  <p>I tried that today, but it only shows the first LE Advertising Report for a device (like hcitool does without the --duplicates option):</p>
  
  <pre><code>$ sudo bluetoothctl
  [NEW] Controller 5C:F3:70:62:68:28 BlueZ 5.38 [default]
  
  [bluetooth]# power on
  Changing power on succeeded
  [CHG] Controller 5C:F3:70:62:68:28 Powered: yes
  
  [bluetooth]# scan on
  Discovery started
  [CHG] Controller 5C:F3:70:62:68:28 Discovering: yes
  [CHG] Device C8:0F:10:29:4E:75 RSSI: -72
  [CHG] Device C8:0F:10:29:4D:98 RSSI: -65
  
  [bluetooth]# devices
  Device C8:0F:10:29:4D:98 MI1S
  Device C8:0F:10:29:4E:75 MI1S
  </code></pre>
  
  <p>How do you use bluetoothctl to capture repeated LE Advertising Reports from the same device, like hcitool does with the --duplicates option?</p>