Counting will really take loooong!

The total numbers are:

$\green{\text{Total such numbers }} = 9999-1000+1 = 9000$

We can count the numbers which have No digit repeated as follows

$\orange{\text{No digit repeated }} = \underbrace{9}_{\text{1st digit } \ne 0} \times \underbrace{9 \times 8 \times 7}_{\text{The order follows}} = 4536$

Using the inclusion-exclusion principle:

$\begin{aligned} \green{\text{Total such numbers }} &= \orange{\text{No digit repeated }} + \blue{\text{ At least one digit repeated}} \\ \green{9000} - \orange{4536} &= \blue{\text{ At least one digit repeated}} \\ \boxed{4464} &= \blue{\text{ At least one digit repeated}} \end{aligned}$