Sure! Here's a test case generator for the problem "What is the Number in my Mind?"

```python
import random

def generate_unique_number(L):
    digits = random.sample('0123456789', L)
    return ''.join(digits)

def generate_try_hit_blow(secret_number):
    L = len(secret_number)
    try_number = generate_unique_number(L)
    hit = sum(1 for x, y in zip(secret_number, try_number) if x == y)
    blow = sum(1 for x in try_number if x in secret_number) - hit
    return try_number, hit, blow

def tcgen():
    test_cases = []
    
    while True:
        L = random.randint(4, 10)
        H = random.randint(1, 10)
        secret_number = generate_unique_number(L)
        
        hints = []
        for _ in range(H):
            try_number, hit, blow = generate_try_hit_blow(secret_number)
            hints.append(f"{try_number} {hit} {blow}")
        
        test_cases.append(f"{L} {H}")
        test_cases.extend(hints)

        # Randomly decide if we should stop generating more hint sets
        if random.random() < 0.3:
            break
    
    test_cases.append("0 0")
    
    return '\n'.join(test_cases)

# Example usage
if __name__ == "__main__":
    print(tcgen())
```

This script will generate test cases for the given problem statement. The function `tcgen` creates multiple hint sets until a random stopping condition is met (approximately 30% chance to stop after each set). Each hint set has a random length for the number of digits (between 4 and 10) and a random number of hints (between 1 and 10).

The function `generate_unique_number` ensures that the generated numbers have unique digits, and `generate_try_hit_blow` computes the try, hit, and blow values for each hint based on a chosen secret number.

The generated test cases include multiple hint sets and conclude with "0 0" to indicate the end of input, as specified in the problem statement.