Is it true that a word that consists of two adjective words has a neutral tone on the second word?
I don't think so.

冰凉冰凉, 雪白雪白, and 通红通红 might or might not have neutral tones.

漂漂亮亮 often have neutral tones, but loot at 浑浑噩噩.

I think neutral tone is a phenomenon in speaking, words like 浑浑噩噩 that is not often used in speaking don't have neural tone.

Note, I did not say they have or they don't have,  it depends on your tone of voice. If people want to be clear or serious, they don't use neutral tone. If they want to be lazy or natural, they use neutral tone.

There are no strict rules.  

If you want to use neutral tone, it will be the B in ABAB and AABB. Since neutral tone always on the last character of a word.