It's weird to use two shampoos at a time.... I'm using SEAH's hair mask (Pearl) for almost a year, finished a full bottle and the results are superb but I've not tried their shampoo. ^^;; Sorry, not much of help.

Btw, SEAH is a new range, reviews might come a bit late?

Well, i not using the range u r saying but i using other in Schwarzkopf.. they told me to use it every 2/3days only bcoz tat shampoo will be too dry for our hair if use it everyday.. maybe urs is same like mine..

Haven't tried the SEAH range... but the current 2 Schwarzkopf shampoos that I'm using are from the BC Bonacure Hairtheraphy range, and they're working like a charm.
Currently alternating between the Repair Rescue shampoo (to moisturize) and the Hair Scalp Deep Cleansing shampoo (to control scalp sebum production) daily, together with the Repair Rescue conditioner.
I think double cleansing for hair is a good idea as it's very effective in solving more than 1 of your hair problems at once. 

Yup, alternating as in use A today, then B tomorrow, then back to A the following day and so on. 
I think whether or not it's okay to shampoo everyday is quite subjective and depends on your hair type and routine.
If your hair is very dry or badly damaged by chemicals, then wash it once every 2 days if possible, especially if you're always indoors. Unless you feel it's damn dirty. Or else, use a treatment shampoo once every few days (for a good boost of moisture). Of which I'm assuming that's what your salon recommended to you right - the Calming Bath one? If oily, then can try washing everyday. Even more so if you're always out and about in our hot and humid Malaysian weather, whereby in this case, alternating between a scalp-cleansing shampoo (to deep cleanse) and moisturizing shampoo (to protect) is good for maintaining balance for your hair and keep it staying healthy.