Can bidder make a preemptive call and later raise his own preemptive call?

For example: North opens the bidding: N 2H E Pass

For example: North opens the bidding: N 2H
E Pass
S Pass
W 2S

At this point is it legal for N to bid 3H. It may be unwise, but is it illegal?

or:For example: North opens the bidding: N 2H E Pass S Pass W 2SAt this point is it legal for N to bid 3H. It may be unwise, but is it illegal?

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