Does one call relate to the last call?

[hab_in_exile]

Don't think so much! You are simply there to report what happens. You don't really decide if it was a charge/block so much as you report wether it was or not. The players decide, you just tell everyone what happened.
If someone asks you what time it is and you say that it is 2:25, and you are asked again in 5 minutes you would say it was 2:30 (assuming your watch works!). Same with officiating, you just tell everyone what happened.