CF10 is evaluating strings with comma's as complex types (Array), formerly they were just Strings

Coldfusion 10's behaviour appears to have changed in the evaluation of strings with commas.

Example:

FORM.IDS = 123456, 654321, 789101  (Form Submission)

<cfset fieldname="IDS" />

<cfset test1 = FORM[fieldname] />

<cfset test2 = evalute("FORM.#fieldname#") />

In Coldfusion 9 the value of test1 and test2 is reported as "123456, 654321, 789101".

In Coldfusion 10 the value of test1 and test2 is reported as an array. "Array (3)".

Is this expected behaviour?  This is jacking up an application we are trying to upgrade and did not expect this one.  Any help will be much appreciated.

Cheers

Lee