Is it okay to stack a 2mm rubber mat on top of the stock LP120 felt mat?

Mat is the Fluance rubber mat. Website says it's actually 2.5 mm. I stacked it on top of the felt mat. Will doing this cause any damage to records or the turntable? I stacked the mats in order to level the VTA and get rid of sibilance. Tracking force is 2.0 when I weighed it. The music sounds better but not sure if I'm doing damage.

 

Unless you are trying to achieve a higher surface on your platter (adding layers of mats,) I would just use the rubber mat. Rubber over felt doesn't get you anything (imo) sound-wise.
The felt mat is not heavy, so there will be no damage to your turntable.

 

I'm definitely trying to get a higher surface so that the tonearm is more level

 

Yes, that is fine to do that.

 

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Providing the height is appropriate for your vta, you may get better sound by using two rubber mats compared to a felt+rubber mat combo.

 

i actually don't like how the rubber mat sounds (music sounds less detailed to me when using it), except for super-bright records like Metallica's Hardwired. But anyway, the reason I didn't get two rubber mats is because I was told there'd be slippage because the rubber mat i bought isn't completely flat like my stock felt mat (it has indentations). Anyway, I can't spot any audible difference between the rubber mat by itself and the rubber mat on top of the felt mat.

 

I've done the same in the past when my arm didn't have any provisions to adjust VTA.