mouser solved it in #mircryption, but requested i put the solution in the forums for future reference, so here it is:

Background: I have a Tcl script which (when given a !command) fetches information from a given webpage and displays the info in the channel.

Problem: The eggdrop always displays the info twice, like an echo. This becomes very annoying after a while. ;)
Also, it works like it should if I send the !command in plaintext, however, it displays the info encrypted (in contrary to how I've configured PlainTextBlock).

Solution: Put the mircryption script last in your configuration file, like:

##### SCRIPTS #####
source scripts/alltools.tcl
source scripts/action.fix.tcl
source scripts/myownscript.tcl
source scripts/tcleggdrop_mcpsfuncs.tcl
source scripts/PlaintextBlock.tcl

Problem solved.

Thanks for the help mouser! :)