Number of consonants = 5
Number of vowels = 4
Number of alike vowels = 2
Consider the vowels as one object so that there are 6 objects to be arranged, namely; M, T, H, L, N, AAIO. Note that AAIO can be arranged within their group.
$N = 6! \times \dfrac{4!}{2!} = 8,640 ~ \text{ways}$