doubt when Arduino connects to multiple i2c devices
Yes, you are correct. Resistance goes low and that is not good for your devices, as the maximal current going through pull-down transistors will increase for several times. 

But it also depends on your wiring configuration, wires length and protocol bitrate. Typically you can have several pull-up resistors closer to the I2C devices.

Please reed this article: I2C Bus Pullup Resistor Calculation

And this answer: Is there a correct resistance value for I2C pull-up resistors?

Check the resistors values. If the resulting resistance is above 2 kOhm @ 400kHz-1MHz, then you are more or less safe. On 100kHz you can use higher resistor values up to 10 kOhm in total.