If follow up questions have very little to do with the original content, make a new topic as you will get more help that way. (I split it because of that)
About your question:
A power symbol (i assume this is what you call a “power point”) is nothing else then a fancy global label. So any such label with the same name (in this case +3v3) will be connected over all hierarchical sheets.
If you do not want to have two such things connected you have a few options.
Option 1 (for small circuits):
Use no labels at all. Just directly connect everything
Option 2 (the kind of simple way):
Use global labels instead of power symbols. Name the labels differently for both your 3v3 systems. (Example would be: +3v3_MCU, +3v3_Analog; Or simply +3v3_1, +3v3_2 depending on your exact usecase and your preferences)
Option 3 (Option 2 but with custom power symbols):
Creating a power symbol is not really hard but at the same time not straight forward either.
I would create a project local symbol library for creating such a specialized power symbol.
A power symbol consists of one invisible power input pin. (This is the thing that creates the label) The pin name is what will become the label name.
In addition it normally has some grapical elements that help the user identify it (completely optional but highly suggested)
The symbol reference must start with “#” and you should set the “is a power symbol” flag in the symbol properties. (The “#” tells kicad not to include this symbol in the BOM and not to try to find a footprint for it)
It is suggested to use the same symbol name as pin name. (Makes it easier for the user to identify which label will be created. Again optional but highly suggested)
Option 3a (use power symbols already in the lib)
If you find two different power symbols in the lib that fit your needs (Names are different and you can work with these names) then you can use them instead of designing your own power symbols.
A bit more sophisticated would be to design your schematic such that you can use hierarchical design. In such a case i would not use any global labels at all and accomplish everything with local labels or hierarchical pins.