Do you suspect that their behvaiour will depart from damped simple harmonic motion?

Making one bob three times more massive than the other will (broadly) make its decay time constant longer by a comparable amount - the details will depend on the drag model you use for the bob (smooth surface, laminar flow; or rough and turbulent?)

If you've got the data, I'd fit an exponential decay to their amplitudes and show that their characteristic timescale varies by something like their masses.

To compare the path of two spherical pendulums in 3D space, you can follow these steps:

First, define the equations of motion for each pendulum. These equations will describe the position and orientation of each pendulum as a function of time.

Solve these equations of motion numerically using a computer program or mathematical software such as MATLAB or Python. This will give you a set of data points that describe the trajectory of each pendulum over time.

Plot the trajectory of each pendulum in 3D space. You can use a 3D plotting software such as MATLAB's "plot3" or Python's "matplotlib" library to create these plots.

Compare the trajectories of the two pendulums visually by overlaying the plots. You can adjust the colors and styles of the plots to make them easier to distinguish.

Analyze the trajectories of the two pendulums by comparing their shapes, amplitudes, frequencies, and other characteristics. You can also use statistical techniques such as correlation analysis to quantify the similarity between the two trajectories.

Draw conclusions based on your analysis. Depending on your research question, you may be interested in identifying similarities or differences between the two pendulums, or in understanding the factors that influence their motion.