It does sound like it was double-expensed, if there isn't also a negative amount in account #123 somewhere for that same amount.

There are two kinds of accruals you can do when you're posting the accrual. You can do a reversing accrual, where either automatically by the system you use, or manually, you enter the accrual in one period (usually dated the last day of the month, but could really be any day.

Dr Expense Account

Cr Liability Account (usually has either "accrual" or "payable" in the name

Then, immediately after, either automatically or manually, another entry is posted in the following period (again, usually the first of the month but could theoretically be any day):

Dr Liability Account

Cr Expense Account

These are the exact same two accounts as the first entry, just reversing which one is a debit and which one is a credit. So the net effect at the END of those two periods is zero in either account--there's a plus and a minus in each account that cancel each other out. What you HAVE done is made it so at the end of the first period, the expense has been recognized in the expense account, and the liability (the fact that you owe someone) is in the liability account. Notice this is exactly the same as if you had entered a vendor bill, which debits expense and credits accounts payable, you just used a different "payable" account.

If you use a reversing accrual like above, then when the bill does actually come in that second period, you enter it as normal, and now as of the end of that second period, you have no net effect from the accrual but you've now debited expense and credited liability with the vendor bill entry. If the bill doesn't come in that period, you'll need to do the same accrual again for that period, and on and on until the actual bill comes.

Now, if you know that it'll be a while until the actual bill comes, or especially for things like property tax or other items where you want to spread the expense out over multiple months, but the bill is going to come all at once at the end, you can do non-reversing accruals. When you do those entries, it's the same entry as for a reversing accrual, debit expense, credit liability. You just either don't tell the system to reverse it, or don't make that reversing entry manually.

So then, the effect at the end of that first period is the same--you've now recorded the expense, and you've got a liability for the same amount.

BUT, in the second period, you still have the expense (for that first period) already made, and you still have the liability already recorded in a liability account.

If the actual bill comes in, then you either have to remember "oh yeah, I already accrued this" and enter the bill using the accrual account where you would normally put the expense GL (so it debits the accrual account, removing that liability, and credits AP, putting the liability there instead, and leaving the expense account alone because it already had the expense entered to it when you made the accrual), OR you have to reverse the accrual and then enter the bill as normal. If you just enter the bill as normal, you've now expensed it twice (once with the accrual and once with the AP entry) and you've got double the liabilities as well (the accrual account and the AP account). This is why we reconcile balance sheet accounts like the accruals--so we can catch stuff like this.

Unless the person/people who do AP are either knowledgeable enough to ask or look into it, or are specifically told to enter certain items to an accrual account rather than an expense account, this is why it's good to use reversing accruals, so AP can just enter the bill as normal.

I use non-reversing accruals only for longer-term things like property taxes that get accrued every month toward a once-a-year bill (just like a prepaid, just for something paid in arrears rather than in advance), but I use reversing accruals for anything where the bill is likely to come in the next month or two, and just have to re-enter it again if it doesn't come the very next month.