[Intermittent] Two pings with "Play" method are generated when clicking the progress bar while on Replay/Close view

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox Developer Edition 59.0b7
• Firefox Nightly 60.0a1 (02/09/2018)
• Min-Vid Shield Study Onboarding 0.4.7 - Shield Study

[Affected Platforms]:

• All Windows

[Prerequisites]:

• Latest Min-Vid v.0.4.7 Shield Study Onboarding ("active" or "activeAndOnboarding" variant) was previously installed on a clean profile.

[Steps to reproduce]:

1. Open the browser with the profiles from prerequisites and navigate to YouTube.
2. Send a video to the player and fast forward it to its end.
3. Click the progress bar.
4. Go to "about:telemetry" and observe how many pings are generated when clicking the progress bar.

[Expected result]:

• One ping is generated.

[Actual result]:

• Two pings are generated.

[Notes]:

• Here is a screen recording of the issue: