HI Zabi,To avod this you can simply show the Loading Symbol which is standard loading symbol..so once user will click he will see the loading symbol and till that time button will be automatically disable and he will not be able to click again..Its good to show loading symbol , so user will come to know it is porcessing ..You can refer below code for the same..
Please check with this and let me know if it helps you..Thanks,Sandeep<apex:actionstatus id="loading" startText="Requesting...">
<apex:facet name="start">
<div id="salesforceSource_blurybackground" style="position:absolute; left:1px; top:1px; width:100%; height:100%; text-align:center; vertical-align: middle; background-color: ⌗dcdcdc; opacity:0.7;filter:alpha(opacity=60)"></div>
<div id="ManageMembersViewport_loading" class="waitingSearchDiv" style="width: 100%; height: 80%; display: ''; ">
<div style="width: 144px;vertical-align: middle;" class="waitingHolder">
<table align="center" valign="top" style="width: 100%; height: 30%">
<tr align="center" valign="top" style="width: 100%; height: 30%">
<td valign="top"><img src="/img/loading.gif"/><span class="waitingDescription"><b>Loading...</b></span></td>
</tr>
</table>
</div>
</div>
<div id="ManageMembersViewport_loading" class="waitingSearchDiv" style="width: 100%; height: 100%; display: ''; "/>
<script>document.getElementById('ManageMembersViewport_loading').height = window.innerHeight * (3/4);</script>
</apex:facet>
<apex:facet name="stop"></apex:facet>
</apex:actionstatus>
status = "loading"
syntax to use where we want loadding symbol.
