I haven't looked at Vulcan Energy at all @canadianaussie but I know about voluntary escrowed shares.
Basically, Yes, the shares have already been issued, some time ago, and are already counted in the shares on issue, so there is zero dilution from this due to them coming out of voluntary escrow. Voluntary Escrow simply means that the owners of the shares have voluntarily agreed to NOT sell the shares for a specific period of time, and have signed a legally binding contract that actually prevents them from selling. This is usually done either when shares are used for payment or part-payment of an acquisition, or when a company is floated.
A real-world example is IPH the ASX-listed patent attorney firm, which had escrow arrangements in place for all of the original vendors who owned the business prior to the float on the ASX. They were all issued shares as part of the float, but all agreed not to sell them until after the IPH full year results announcements were released in what I think was the second or third full year after the float. The reason was to stop them from cashing out too early and crashing the share price before the company had a chance to establish a track record as a listed company. In reality, those that did want to sell after their shares were "released from escrow" (i.e. after the agreed time period had finished or elapsed) did so in an orderly fashion, not all at once. It's not in their interests to crash the share price when they have a lot of shares to sell, and that goes double for smaller companies with less liquidity.
The second common way I've seen escrowed shares work is when a company acquires a smaller company and pays the founder of that company either fully or partly in shares. It is not uncommon for escrow arrangements to be agreed to so that the vendor (the seller of the business) can't sell those shares for a specific period of time. Quite often, the vendor is employed by the acquirer of the business to continue to run the business, or continue to work within that business unit, but working for the business acquirer instead of for himself/herself as they did before. In that case, the escrow arrangements also act as an added incentive to keep the vendor focussed on value creation, i.e. doing a good job, as he won't want to see the price of his shares deteriorate during the escrow period - he will want to see them as high as possible when they are released from escrow. However, I have also seen plenty of situations where escrow arrangements are put in place during business acquisitions where the seller takes the shares and moves on, leaving the business. There are various reasons why the buyer would insist on escrow arrangements, but if the seller is keen enough to sell, they'll agree to those terms.
In terms of what it means for ordinary shareholders when shares are released from escrow, it all depends on whether they get sold (they might not), and how many of them get sold, and over what time period. If it's done gradually, there may be very little effect on the SP. If the shares are sold in large quantities too quickly, it can certainly put downward pressure on the share price. Hopefully these ones, if they are sold, will be sold gradually. That way it benefits everybody, including the seller of the shares.
Hope that helps.