How to add legend when using twinx

I am trying to plot 2 values with same x axis values (time) but different y axis values. I am trying to add legend to the plot, however, I keep getting 2 legends for the same variable instead of one legend for each variable.

This is the code i have used.

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
from datetime import datetime, timedelta

# Assuming you have the time series data in numpy arrays named x_values, y_values, and fire_counts
df=pd.read_csv('FireCountPenchMar2012.csv')
print(df)

xaxis=np.arange(0,248,1)
yaxis=hdwi
yaxis2=df.fire_count
print(yaxis2)

# Step 1: Create the dates for the x-axis based on the starting date (1 March 00:00 UTC)
start_date = datetime(2023, 3, 1, 0, 0, 0)
dates = [start_date + timedelta(hours=3*i) for i in range(len(xaxis))]

plt.figure(figsize=(15,10))

# Step 2: Plot the first time series with dates on the x-axis
plt.plot(dates, yaxis, 'o-g', label='HDWI')

# Step 3: Format the first y-axis and add axis labels and a title
plt.ylabel('HDW')
plt.title('HDWI v/s Fire Counts')

# Step 4: Create a second y-axis for the 'fire_counts' variable
ax2 = plt.gca().twinx()
ax2.scatter(dates, yaxis2, color='red', label='Fire Counts')
ax2.set_ylabel('Fire Counts')

# Step 5: Show the legend for both lines (y_values and fire_counts)
lines, labels = plt.gca().get_legend_handles_labels()
lines2, labels2 = ax2.get_legend_handles_labels()

# Combine the handles and labels for both legends
all_lines = lines + lines2
all_labels = labels + labels2

# Display the combined legend
plt.gca().legend(all_lines, all_labels)

# Step 6: Format the x-axis to display dates at regular intervals (e.g., every 2 days)
date_format = mdates.DateFormatter('%b %d')
plt.gca().xaxis.set_major_locator(mdates.DayLocator(interval=2))
plt.gca().xaxis.set_major_formatter(date_format)

# Step 7: Rotate the x-axis date labels for better readability
plt.xticks(rotation=45)

# Step 8: Adjust the layout and display the plot
plt.grid()
plt.tight_layout()
plt.show()here

The legend in this figure should highlight the issue

The figure as obtained in the output with repeating legend

For a detailed explanation, please refer to this answer.

from matplotlib.pyplot import show, subplots

# make the twin Axes
fig, ax0 = subplots()
ax1 = ax0.twinx()

# plot two lines in the 1st Axes, label them
ax0.plot((0, 1, 2, 3, 4), color='g', label='green')
ax0.plot((4, 3, 2, 1, 0), color='k', label='black')

# make a scatter in the 2nd Axes, label it
ax1.scatter(( 1,  2,  3),
            (41, 37, 23), color='r', label='red')

# collect handles and labels in a list of lists [[h0, l0], [h1, l1]]
handles_labels = [ax.get_legend_handles_labels() for ax in (ax0, ax1)]

# but Axes.legend needs h=h0+h1 and l=l0+l1, so
# ① transpose hl → [[h0, h1, [l0, l1]]
hl_transposed = zip(*handles_labels)
# ② sum the sub-lists in the list of handles and in the list of labels
handles, labels = [sum(handles_or_labels, [])
                      for handles_or_labels in hl_transposed]

ax0.legend(handles, labels)
show()