Internet poker - Should you play one table or two?

[Mike Haven]

let's say to win $1000 gross on a $20-$40 table you have to win ten pots

so you pay $30 in rake

proportionally, to win $500 on a $10-$20 table you have to win ten pots

but you still pay $30 in rake

therefore to win $1000 on two $10-$20 tables you have to win twenty pots

and pay $60 in rake

your winnings are the same but your business expenses are twice as much

am i right in thinking it is better to double your stakes than play two tabls?