I learned (Destruction reduced 10% magica regenerates 25%)
There is a perk where I can put 2 enchantments on 1 item
is the above enchantment considered 2 or 1?
Can I enchant an item with 2X (Destruction reduced 10% magica regenerates 25%) to make it (Destruction reduced 20% magica regenerates 50%)?

The enchantment that gives you both effects at the same time is considered one enchantment. But you can't put the same enchantment on the same item twice, if you want two enchantments on an item you have to choose two different ones.

If you only want Fortify Destruction and Fortify Magicka Regen on the item, and no other effect, I would suggest doing it with a separate enchantment for each effect. IIRC that will give you a stronger effect for each than using the single enchantment that combines them.

Fortify Destruction base magnitude, -8% casting cost (combined enchantment, -5%)
Fortify Magicka Regen base magnitude, +20% (combined enchantment, 10%)

The base magnitude for the enchantment that combines them gives you *less* of a bump to each effect.