managing waypoints

I am using MaxSea TZ software on my PC to manage waypoints on my Furuno NN3D MFD12.

I would edit waypoints on the computer, download file to SD card, then upload file via SD card to MFD.

I found that I ended up withduplicate (really, up to 5 copies) of the same waypoint for EACH waypoint I had. I soon maxed out my waypoint capacity (I believe 10,000 ?) So I painstakingly deleted each duplicate (up to 5 times) waypoint on the MaxSea TZ software, downloaded to SD card; erased all waypoints on the MFD, then uploaded to the MFD.

Now I am finding I have about 2,000 waypoints on the MFD in 5 categories (e.g., Local, Group, Symbol, etc) = 10,000 waypoints. I am still maxed out. I can't hit MOB to add more waypoints or mark a spot.

My questions:
1) How do I erase the duplicate (5x/5 copies) of the waypoints and just have the 2,000 waypoints so I can free up space to add MOB/waypoints ?

2) After a trip on the boat after adding waypoints, I'm now afraid to download the waypoints to SD card and then read into MaxSea TZ because I don't want to duplicate waypoints again. Do I have to clear all waypoints either on the MFD or MaxSea before uploading the waypoint file?

MaxSea software allows merging of points. When you import points, that you previously exported, without clearing the points in the software first; it will merge the two datasets. This will result in duplicates of the same points. The more times you do this; the more duplicates you will have.

The NavNet system does not merge. It will automatically delete any points in the system prior to the importing. (Be careful)

A point stored in the NN3D is counted towards the 10,000 point limit. If you store one point as a Fishing point and then that same point again under another category; that is two points. If you delete the fishing point, the point in the other category is not affected.
If you duplicate a point and put it into 5 different categories, then it will count 5 against your 10,000 point limit. If you need more than 10,000 point limit, then saving the file on the SD card will allow you to clear and save another 10,000 points. This can be done based on whatever you wish. For example: save your Fishing points to one save file and your NAV points to another; restore as needed.