Can't get MCP4725 (I2C) to work

Dear all,

I am trying to hook up a MCP4725 (12-bit DAC) breakout board to the I2C bus of my Raspberry.
No matter that I do in Node-RED, I cannot get it to accept commands and output a voltage corresponding to msg.payload.

I have two of those boards, one configured for I2C address 0x60 and one for 0x61.

i2cdetect can see both of the boards (I connect one at a time) and reports back the right address.
At least: when Node-RED is not running. As soon as it runs, I2C ports 0x3-0x77 are all reported as being occupied, even if I have zero devices on the I2C bus.

Can anyone tell me what is going on here?? Any suggestions are very much appreciated.

FYI: the node I'm using for connecting to the MCP4725 is ncd-red-mcp4725, v 1.0.4.

Problem solved.
It turned out I had 2 different types of I2C nodes in the palette at the same time.
Apparently, that won't work.
After a full reinstall of Node RED, and installing only the MCP4725 library, all worked fine.