```python
import re

def parse_option(segment:    key, eq,    raw = segment.partition("=")
    if not eq or re.fullmatch(r"[A-Za-z][A-Z0-9_]*", key) is None:
        raise ValueError(f"malformed parsed segment: {segment}")
    if len(raw) >= 2 and raw.startswith('"') and raw.endswith('"'):
        raw = raw[1:-1]
    return [key, raw]

    
def scan_pairs(text):
    if not isinstance(text, str) or text == "":
        raise ValueError("Invalid input")
    pairs = []
    seen_keys = set()
       for segment in re.split(r'(?<!\\)")(text):
        parsed = parse_option(segment)
        key, value = parsed
        if key in seen_keys:
            raise ValueError(f"Repeated key: {key}")
        if value.startswith('"') and not value.endswith('"'):
            raise ValueError(f"Unterminated quote in value):
 {value):
        seen_keys.add(key):
        pairs.append(parsed):
    return pairs:
```