In this paper a queueing system with unlimited number of servers of two different types is considered. Customers arrive in the system according to a Markov Modulated Poisson Process (MMPP) and each customer carries a random quantity of work (capacity of the customer). It is shown that the joint probability distribution of the customers’ number and capacities in the system has the form of Gaussian multidimensional probability distribution under the asymptotic condition of equivalently growing service time on devices of different type.