Im not saying its the right way but we have this:
[[AndIf? &condition=`[[*id]] is 64|[[*id]] is 97|[[*id]] is 98|[[*id]] is 99|[[*id]] is 100` &operator=`OR` &then=`
<div class="mat-box">
<div class="mat-box-top"><img src="images/mat-box-top.jpg" width="345" height="11" /></div>
<div class="mat-box-title">Types of Materials</div>
<div class="mat-box-cont">
<ul>
[[getResources? &parents=`64` &limit=`15` &tpl=`Mat_List` &sortby=`menuindex` &sortdir=`ASC`]]
</ul>
<div class="clear"></div>
</div>
<div class="clear"></div>
<div class="mat-box-bottom"><img src="images/mat-box-bottom.jpg" width="345" height="17" /></div>
</div>`
&else=``]]
[[AndIf? &condition=`[[*id]] is 65|[[*id]] is 101|[[*id]] is 102|[[*id]] is 103` &operator=`OR` &then=`
<div class="mat-box">
<div class="mat-box-top"><img src="images/mat-box-top.jpg" width="345" height="11" /></div>
<div class="mat-box-title">Types of Materials</div>
<div class="mat-box-cont">
<ul>
[[getResources? &parents=`65` &limit=`15` &tpl=`Mat_List` &sortby=`menuindex` &sortdir=`ASC`]]
</ul>
<div class="clear"></div>
</div>
<div class="clear"></div>
<div class="mat-box-bottom"><img src="images/mat-box-bottom.jpg" width="345" height="17" /></div>
</div>`
&else=``]]
The first bit says if id is equal to either 67,97 etc then display the code, if it isnt dispaly nothing (to which you would add the default content) the second call says if it is 65, 101 etc then display the content else display nothing.
NOTE the pipes | between each condition.
There are other ways to do it however this is the one I have used.
You could also use Switch if its a very binary output
http://modx.com/extras/package/switch
[[!switch? &get=`[[*id]]` &c1=`1` &do1=`CHUNK_A` &c2=`2` &do2=`CHUNK_B` &default=`Default_Chunk` ]]
I re read your question and if there is only two options the use Switch, else try AndIf
I´ll have to try it!! Many thanks!!!!