I use tinymce for a webpage that dynamically generates at least 5 texts.
The configuration I use only works on the first textarea
unfortunately.
You should use different mode in your configuration. For example mode: "specific_textareas" to work for all textarea with a given class which is specified in the editor_selector parameter.
In order to work on all textareas with class mceEditor you can use this:
tinyMCE.init({
mode : "specific_textareas",
editor_selector : "mceEditor",
.....