Temperature sensors TMP36 and LM35 have temperature diff. (offset) in the same circuit
The sensors have different accuracy, according to their datasheets.
The TMP36 has ±2°C typical accuracy, while the the LM35 has 0.5°C typical accuracy (over 25°C).
Read the datasheet carefully and pay attention to the characteristics, more specifically to the accuracy error graphs for each sensor. At your measured temperature (~17°C), you should expect the following error (the red line is not super accurate, but should give a general clue):

LM35:



TMP36:



In addition, as Michal stated, you might have noise in your circuit, and you are not connecting the TMP36 as per the datasheet suggests (note the capacitor between +V and Ground):