Consider my case:
Same serial number on several android devices. Adb is useless. How can I change the serial number?
So I did'nt solved the problem with the ADB but to identify an Android device I use this code (use getDeviceId(context)):
public static String getDeviceId(Context context) {
    String id = getUniqueID(context);
    if (id == null)
        id = Settings.Secure.getString(context.getContentResolver(), Settings.Secure.ANDROID_ID);
    return id;
}
private static String getUniqueID(Context context) {
    String telephonyDeviceId = "NoTelephonyId";
    String androidDeviceId = "NoAndroidId";
    // get telephony id
    try {
        final TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
        telephonyDeviceId = tm.getDeviceId();
        if (telephonyDeviceId == null) {
            telephonyDeviceId = "NoTelephonyId";
        }
    } catch (Exception e) {
    }
    // get internal android device id
    try {
        androidDeviceId = android.provider.Settings.Secure.getString(context.getContentResolver(),
                android.provider.Settings.Secure.ANDROID_ID);
        if (androidDeviceId == null) {
            androidDeviceId = "NoAndroidId";
        }
    } catch (Exception e) {
    }
    // build up the uuid
    try {
        String id = getStringIntegerHexBlocks(androidDeviceId.hashCode())
                + "-"
                + getStringIntegerHexBlocks(telephonyDeviceId.hashCode());
        return id;
    } catch (Exception e) {
        return "0000-0000-1111-1111";
    }
}
public static String getStringIntegerHexBlocks(int value) {
    String result = "";
    String string = Integer.toHexString(value);
    int remain = 8 - string.length();
    char[] chars = new char[remain];
    Arrays.fill(chars, '0');
    string = new String(chars) + string;
    int count = 0;
    for (int i = string.length() - 1; i >= 0; i--) {
        count++;
        result = string.substring(i, i + 1) + result;
        if (count == 4) {
            result = "-" + result;
            count = 0;
        }
    }
    if (result.startsWith("-")) {
        result = result.substring(1, result.length());
    }
    return result;
}
I use it to identify a specific app installation when calling my web services. As you can see I try different approches, based also on TelephonyManager and ANDROID_ID.
What I get is a string like xxxx-xxxx-xxxx-xxxx where x is an hex character.
I bought a lot of low cost China tablets and all of these have the same DEVICE_ID and the same serial number !! So my solution. It's working well for now.