Working on my taxes for 2019 and came upon this scenario. I lived at my parents' house for 10 months and my own place for two, but was working at the same job as a contractor in both locations. Because of this I have two home office deductions. TurboTax asks for "expenses allocated to this home office" for each home office. Most of what I'm deducting was used in both locations, such as computer monitors, cables, etc. But there were also items I only used in my apartment like a desk and a chair that I bought specifically for work. What does it mean to allocate expenses between the offices?
Home office expenses typically refers to the cost of the house's costs (electricity, phone + internet, water, rent, property taxes, mortgage interest and so on) that you pay for, multiplied by the fraction of the house floor area occupied by the area used exclusively as your office. Since those are typically monthly, I'd just allocate them to the office you were using in the month they were paid.
Your office chair and desk are assets of your business, not of the office where they sit. Depreciate them separately.
Cables, unless they're really expensive, are an expense of the business at the time you bought them. They also don't belong to an office.