from tkinter import ttk
import tkinter as tk


blow = [("january", "2013"),("february", "2014"),("march", "2015"),("april", "2016"),("may", "2017")]

def append_select():
    cur_id = tree.focus()

    for child in tree2.selection():
    #for child in tree2.get_children():
        if cur_id in child:
            print("item exist")
        elif cur_id:
            tree2.insert("", tk.END, values=tree.item(cur_id)['values'])


root = tk.Tk()
root.geometry("500x500")

tree = ttk.Treeview(columns=("columns1", "columns"), show="headings", selectmode="browse")
tree.heading("#1", text="Month")
tree.heading("#2", text="Year")
for n in blow:
    tree.insert("", tk.END, values=(n))
tree.pack()

b1 = tk.Button(text="append", command=append_select)
b1.pack()

tree2 = ttk.Treeview(columns=("Month", "Year"), show="headings")
tree2.heading("#1", text="month")
tree2.heading("#2", text="year")
tree2.pack()

root.mainloop()