------
## 最终结论
```python
def check_isosceles(a, b, c):
    return a == b or a == c or b == c

# Test cases
assert check_isosceles(6, 8, 12) == False
assert check_isosceles(6, 6, 12) == True
assert check_isosceles(6, 16, 20) == False
```