yes you can put multiple cascading forms on a single dashboard. Here is one example.
<form>
<label>Multiple Cascading Forms</label>
<description>Example of placing form elements within a panel.</description>
<row>
<panel>
<input type="dropdown" token="username">
<default>*</default>
<choice value="*">All</choice>
<populatingSearch fieldForValue="user" fieldForLabel="user" earliest="-24h" latest="now">
<![CDATA[index=_internal | stats count by user]]>
</populatingSearch>
</input>
<input type="radio" token="source">
<default>*</default>
<choice value="*">All</choice>
<populatingSearch fieldForValue="sourcetype" fieldForLabel="sourcetype" earliest="-24h" latest="now">
<![CDATA[index=_internal user=$username$| stats count by sourcetype]]>
</populatingSearch>
</input>
<table>
<title>Table of events</title>
<searchString>index=_internal user=$username$ sourcetype=$source$ | head 100 | table _time, user, sourcetype</searchString>
<earliestTime>-24h@h</earliestTime>
<latestTime>now</latestTime>
</table>
</panel>
<panel>
<input type="dropdown" token="sourcetype1" searchWhenChanged="true">
<label>Source types for _Internal All</label>
<choice value="*">All</choice>
<choice value="splunkd">splunkd</choice>
<choice value="splunk_web_access">splunk_web_access</choice>
<default>splunkd</default>
</input>
<chart>
<title>_Internal All</title>
<searchString>index=_internal sourcetype="$sourcetype1$" | timechart count</searchString>
<earliestTime>-4h@h</earliestTime>
<latestTime>now</latestTime>
<option name="charting.chart">line</option>
<option name="charting.legend.placement">none</option>
</chart>
</panel>
</row>
</form>
SGF
