Selective nesting

Let's say I have the following vector of nested strings in APL+WIN

x{<-}'aaa' 'bbb' 'ccc' 'ccc' 'ddd'

I want to nest those that are the same eg.

.…---------------------.
|.…-..…-..…-------..…-.|
||aa||bb||.…-..…-.||dd||
|'--''--'||cc||cc||'--'|
|        |'--''--'|    |
|        '¹-------'    |
'¹---------------------'

One option is to use dyadic enclose to nest all of them

(x{iota}x){enclose}x

.…---------------------------.
|.…---..…---..…-------..…---.|
||.…-.||.…-.||.…-..…-.||.…-.||
|||aa||||bb||||cc||cc||||dd|||
||'--'||'--'||'--''--'||'--'||
|'¹---''¹---''¹-------''¹---'|
'¹---------------------------'

And then selectively disclose the ones with shape of one, but that's
got me stumped too!  Any pointers?

Thanks.