Is it possible to compare data from multiple rows of a grid, see if they are the same, and hide the duplicates?

event-list.html

<div id="event">
  <ul class="menu-list__event">

    {{entries:listing folder="events" show_future="yes" show_past="yes" conditions="venue:allen"}}

      {{if total_results==!0}}

        {{if first}}
          <li class="{{venue}}">
            <span class="menu-list-header">In the Allen Room</span>
            <ul>
        {{endif}}
              <li>
                <span class="menu-dates">
                  {{datetimes limit="1"}}
                    {{date format="D. M. j"}} <!-- THIS LINE RIGHT HERE is pulling in the dates - right now i have it limited to 1 date as a temporary solution but i'd like to have it list all dates from that grid (with an ampersand in between) but not list multiple dates if they are the same. -->
                  {{/datetimes}}
                </span>
                <em class="artist-name">
                  {{if shorttitle}}
                    {{shorttitle}}
                  {{else}}
                    {{title}}
                  {{endif}}
                </em>
              </li>
        {{if last}}
            </ul>
          </li>
        {{endif}}  

      {{endif}}

    {{/entries:listing}}

    {{entries:listing folder="events" show_future="yes" show_past="yes" conditions="venue:penthouse"}}

      {{if total_results==!0}}

        {{if first}}
          <li class="{{venue}}">
            <span class="menu-list-header">In the Penthouse</span>
            <ul>
        {{endif}}
              <li>
                <span class="menu-dates">
                  {{datetimes limit="1"}}
                    {{date format="D. M. j"}}
                  {{/datetimes}}
                </span>
                <em class="artist-name">
                  {{if shorttitle}}
                    {{shorttitle}}
                  {{else}}
                    {{title}}
                  {{endif}}
                </em>
              </li>
        {{if last}}
            </ul>
          </li>
        {{endif}}  

      {{endif}}

    {{/entries:listing}}

    {{entries:listing folder="events" show_future="yes" show_past="yes" conditions="venue:atrium"}}

      {{if total_results==!0}}

        {{if first}}
          <li class="{{venue}}">
            <span class="menu-list-header">In the Atrium</span>
            <ul>
        {{endif}}
              <li>
                <span class="menu-dates">
                  {{datetimes limit="1"}}
                    {{date format="D. M. j"}}
                  {{/datetimes}}
                </span>
                <em class="artist-name">
                  {{if shorttitle}}
                    {{shorttitle}}
                  {{else}}
                    {{title}}
                  {{endif}}
                </em>
              </li>
        {{if last}}
            </ul>
          </li>
        {{endif}}  

      {{endif}}

    {{/entries:listing}}

  </ul>
</div>

events.yaml

title: Event Page

fields:
  shorttitle:
    display: Abbreviated Event Title
      type: text

	datetimes:
		display: Event Date(s) & Time(s)
		type: grid
		fields:
			date:
				display: Event Date
				type: date
			time:
				display: Event Start Time
				type: text
			guid:
				display: SRO GUID
				type: text

	venue:
		display: Event venue
		type: select
		options:
			allen: Allen Room
			penthouse: Stanley H. Kaplan Penthouse
			atrium: David Rubenstein Atrium

	genre:
		display: Genre(s)
		type: suggest
		options: 
			broadway: Broadway
			country: Country
			crossover: Crossover
			folk: Folk
			gospel: Gospel
			indie: Indie Rock
			pop: Pop
			songwriter: Songwriter

	coverphoto:
		display: Event Page Cover Photo
		type: file
		allowed: [png, jpg, jpeg]
		destination: assets/img/cover-photos

	photocredit:
		display: Cover Photo Credit
		type: text

	content:
		display: Event Description
		type: redactor

	fineprint:
		display: Fine Print (sponsors, co-producers, live from LC etc.)
		type: text

	details:
		display: Details (program notes, song list etc.)
		type: grid
		fields:
			file:
				type: file
				allowed: [pdf]
				destination: assets/img/download/
			title:
				display: File Link Title
				type: text

	links:
		display: Artist links
		type: grid
		fields:
			link:
				display: Link URL
				type: text
			title:
				display: Link Title
				type: text

	watch:
		display: Watch Embed Code
		type: textarea

	listen:
		display: Listen Embed Code
		type: textarea

	look:
		display: Look (artist photo galleries)
		type: grid
		fields:
			file:
				type: file
				allowed: [png, jpg, jpeg]
				destination: assets/img/artist-galleries/
			stupid:
				type: text
				display: ignore me

	alsolike:
		display: You Might Also Like
		type: suggest
		create: true
		content:
			folder: events
			label: title
			value: url